diff --git a/scripts/build.sh b/scripts/build.sh
index 71c4e4f..41923fc 100755
--- a/scripts/build.sh
+++ b/scripts/build.sh
@@ -5,7 +5,15 @@ GREEN="\033[0;32m"
 OFF="\033[m"
 NAME="fzf-vcal"
 SRC="./src/main.sh"
-echo "🐔 ${GREEN}Building${OFF} ${BOLD}$NAME${OFF}"
-sed -E 's|@@include (.+)$|cat \1|e' "$SRC" >"$NAME"
+
+tmpdir=$(mktemp -d)
+echo "🐔 ${GREEN}Internalize sourced files${OFF}"
+sed -E 's|\. "([^$].+)"$|cat src/\1|e' "$SRC" >"$tmpdir/1.sh"
+echo "🥚 ${GREEN}Internalize awk scripts${OFF}"
+sed -E 's|@@include (.+)$|cat src/\1|e' "$tmpdir/1.sh" >"$tmpdir/2.sh"
+echo "🐔 ${GREEN}Internalize awk libraries${OFF}"
+sed -E 's|@include "(.+)"$|cat src/\1|e' "$tmpdir/2.sh" >"$NAME"
+echo "🥚 ${GREEN}Make executable and cleanup${OFF}"
 chmod +x "$NAME"
-echo "🥚 ${GREEN}Done${OFF}"
+rm -rf "$tmpdir"
+echo "🍳 ${GREEN}Done:${OFF} Sucessfully built ${BOLD}${GREEN}$NAME${OFF}"
diff --git a/src/awk/approx.awk b/src/awk/approx.awk
index d08e1d1..674eeae 100644
--- a/src/awk/approx.awk
+++ b/src/awk/approx.awk
@@ -3,80 +3,10 @@
 ##
 ## @assign collection_labels: See configuration of the current program.
 
+@include "lib/awk/icalendar.awk"
+
 # Functions
 
-# Unescape string
-#
-# @local variables: i, c, c2, res
-# @input str: String
-# @return: Unescaped string
-function unescape(str,    i, c, c2, res) {
-  for(i=1; i<=length(str);i++) {
-    c = substr(str, i, 1)
-    if (c != "\\") {
-      res = res c
-      continue
-    }
-    i++
-    c2 = substr(str, i, 1)
-    if (c2 == "n" || c2 == "N") {
-      res = res "\n"
-      continue
-    }
-    # Alternatively, c2 is "\\" or "," or ";". In each case, append res with
-    # c2. If the strings has been escaped correctly, then the character c2
-    # cannot be anything else. To be fail-safe, simply append res with c2.
-    res = res c2
-  }
-  return res
-}
-
-# Isolate content part of an iCalendar line, and unescape.
-#
-# @input str: String
-# @return: Unescaped content part
-function getcontent(str) {
-  return unescape(substr(str, index(str, ":") + 1))
-}
-
-# Time-zone aware parsing of the date/date-time entry at the current record.
-#
-# @local variables: dt
-# @return: date or date-time string that can be used in date (1)
-function parse(    dt) {
-  # Get timezone information
-  for (i=2; i<NF-1; i+=2) {
-    if ($i == "TZID") {
-      dt = "TZ=\"" $(i+1) "\" "
-      break
-    }
-  }
-  # Get date/date-time
-  return length($NF) == 8 ?
-    dt $NF :
-    dt gensub(/^([0-9]{8})T([0-9]{2})([0-9]{2})([0-9]{2})(Z)?$/, "\\1 \\2:\\3:\\4\\5", "g", $NF)
-}
-
-# Map iCalendar duration specification into the format to be used in date (1).
-#
-# @local variables: dt, dta, i, n, a, seps
-# @input duration: iCalendar duration string
-# @return: relative-date/date-time specification to be used in date (1)
-function parse_duration(duration,    dt, dta, i, n, a, seps) {
-  n = split(duration, a, /[PTWHMSD]/, seps)
-  for (i=2; i<=n; i++) {
-    if(seps[i] == "W") dta["weeks"]   = a[i]
-    if(seps[i] == "H") dta["hours"]   = a[i]
-    if(seps[i] == "M") dta["minutes"] = a[i]
-    if(seps[i] == "S") dta["seconds"] = a[i]
-    if(seps[i] == "D") dta["days"]    = a[i]
-  }
-  dt = a[1] ? a[1] : "+"
-  for (i in dta)
-    dt = dt " " dta[i] " " i
-  return dt
-}
-
 # Get relative file path.
 #
 # @local variables: n, a
diff --git a/src/awk/get.awk b/src/awk/get.awk
index baaac2b..ad75a9c 100644
--- a/src/awk/get.awk
+++ b/src/awk/get.awk
@@ -3,41 +3,8 @@
 ##
 ## @assign field: Field name
 
-# Unescape string
-#
-# @local variables: i, c, c2, res
-# @input str: String
-# @return: Unescaped string
-function unescape(str,    i, c, c2, res) {
-  for(i=1; i<=length(str);i++) {
-    c = substr(str, i, 1)
-    if (c != "\\") {
-      res = res c
-      continue
-    }
-    i++
-    c2 = substr(str, i, 1)
-    if (c2 == "n" || c2 == "N") {
-      res = res "\n"
-      continue
-    }
-    # Alternatively, c2 is "\\" or "," or ";". In each case, append res with
-    # c2. If the strings has been escaped correctly, then the character c2
-    # cannot be anything else. To be fail-safe, simply append res with c2.
-    res = res c2
-  }
-  return res
-}
+@include "lib/awk/icalendar.awk"
 
-# Isolate content part of an iCalendar line, and unescape.
-#
-# @input str: String
-# @return: Unescaped content part
-function getcontent(str) {
-  return unescape(substr(str, index(str, ":") + 1))
-}
-
-# AWK program
 BEGIN              { FS = ":"; regex = "^" field }
 /^BEGIN:VEVENT$/   { inside = 1 }
 /^END:VEVENT$/     { exit }
diff --git a/src/awk/new.awk b/src/awk/new.awk
index f706f8c..0f7b437 100644
--- a/src/awk/new.awk
+++ b/src/awk/new.awk
@@ -3,40 +3,7 @@
 ##
 ## @assign uid: UID to use
 
-# Functions
-
-# Escape string to be used as content in iCalendar files.
-#
-# @input str: String to escape
-# @return: Escaped string
-function escape(str)
-{
-  gsub("\\\\", "\\\\", str)
-  gsub(";",    "\\;",  str)
-  gsub(",",    "\\,",  str)
-  return str
-}
-
-# Print property with its content and fold according to the iCalendar
-# specification.
-#
-# @local variables: i, s
-# @input nameparam: Property name with optional parameters
-# @input content: Escaped content
-function print_fold(nameparam, content,    i, s)
-{
-  i = 74 - length(nameparam)
-  s = substr(content, 1, i)
-  print nameparam s
-  s = substr(content, i+1, 73)
-  i = i + 73
-  while (s)
-  {
-    print " " s
-    s = substr(content, i+1, 73)
-    i = i + 73
-  }
-}
+@include "lib/awk/icalendar.awk"
 
 # AWK program
 BEGIN { 
diff --git a/src/awk/parse.awk b/src/awk/parse.awk
index 07ad4d0..5f0fa41 100644
--- a/src/awk/parse.awk
+++ b/src/awk/parse.awk
@@ -6,79 +6,7 @@
 ##
 ## @assign collection_labels: See configuration of the current program.
 
-# Functions
-
-# Unescape string
-#
-# @local variables: i, c, c2, res
-# @input str: String
-# @return: Unescaped string
-function unescape(str,    i, c, c2, res) {
-  for(i=1; i<=length(str);i++) {
-    c = substr(str, i, 1)
-    if (c != "\\") {
-      res = res c
-      continue
-    }
-    i++
-    c2 = substr(str, i, 1)
-    if (c2 == "n" || c2 == "N") {
-      res = res "\n"
-      continue
-    }
-    # Alternatively, c2 is "\\" or "," or ";". In each case, append res with
-    # c2. If the strings has been escaped correctly, then the character c2
-    # cannot be anything else. To be fail-safe, simply append res with c2.
-    res = res c2
-  }
-  return res
-}
-
-# Isolate content part of an iCalendar line, and unescape.
-#
-# @input str: String
-# @return: Unescaped content part
-function getcontent(str) {
-  return unescape(substr(str, index(str, ":") + 1))
-}
-
-# Time-zone aware parsing of the date/date-time entry at the current record.
-#
-# @local variables: dt
-# @return: date or date-time string that can be used in date (1)
-function parse(    dt) {
-  # Get timezone information
-  for (i=2; i<NF-1; i+=2) {
-    if ($i == "TZID") {
-      dt = "TZ=\"" $(i+1) "\" "
-      break
-    }
-  }
-  # Get date/date-time
-  return length($NF) == 8 ?
-    dt $NF :
-    dt gensub(/^([0-9]{8})T([0-9]{2})([0-9]{2})([0-9]{2})(Z)?$/, "\\1 \\2:\\3:\\4\\5", "g", $NF)
-}
-
-# Map iCalendar duration specification into the format to be used in date (1).
-#
-# @local variables: dt, dta, i, n, a, seps
-# @input duration: iCalendar duration string
-# @return: relative-date/date-time specification to be used in date (1)
-function parse_duration(duration,    dt, dta, i, n, a, seps) {
-  n = split(duration, a, /[PTWHMSD]/, seps)
-  for (i=2; i<=n; i++) {
-    if(seps[i] == "W") dta["weeks"]   = a[i]
-    if(seps[i] == "H") dta["hours"]   = a[i]
-    if(seps[i] == "M") dta["minutes"] = a[i]
-    if(seps[i] == "S") dta["seconds"] = a[i]
-    if(seps[i] == "D") dta["days"]    = a[i]
-  }
-  dt = a[1] ? a[1] : "+"
-  for (i in dta)
-    dt = dt " " dta[i] " " i
-  return dt
-}
+@include "lib/awk/icalendar.awk"
 
 # Print string of parsed data.
 #
diff --git a/src/awk/set.awk b/src/awk/set.awk
index de97bbd..6bba546 100644
--- a/src/awk/set.awk
+++ b/src/awk/set.awk
@@ -6,21 +6,7 @@
 ##
 ## LIMITATION: This program does not fold long content lines.
 
-# Functions
-
-# Escape string to be used as content.
-#
-# @input str: Content string
-# @return: Escaped string
-function escape(str)
-{
-  gsub("\\\\", "\\\\", str)
-  gsub(";",    "\\;",  str)
-  gsub(",",    "\\,",  str)
-  return str
-}
-
-# AWK program
+@include "lib/awk/icalendar.awk"
 
 BEGIN                 { FS = "[:;]"; zulu = strftime("%Y%m%dT%H%M%SZ", systime(), 1) }
 /^BEGIN:VEVENT$/      { inside = 1 }
diff --git a/src/awk/update.awk b/src/awk/update.awk
index f133988..614ad95 100644
--- a/src/awk/update.awk
+++ b/src/awk/update.awk
@@ -1,42 +1,7 @@
 ## src/awk/update.awk
 ## Update iCalendar file from markdown file.
 
-# Functions
-
-# Escape string to be used as content in iCalendar files.
-#
-# @input str: String to escape
-# @return: Escaped string
-function escape(str)
-{
-  gsub("\\\\", "\\\\", str)
-  gsub(";",    "\\;",  str)
-  gsub(",",    "\\,",  str)
-  return str
-}
-
-# Print property with its content and fold according to the iCalendar
-# specification.
-#
-# @local variables: i, s
-# @input nameparam: Property name with optional parameters
-# @input content: Escaped content
-function print_fold(nameparam, content,    i, s)
-{
-  i = 74 - length(nameparam)
-  s = substr(content, 1, i)
-  print nameparam s
-  s = substr(content, i+1, 73)
-  i = i + 73
-  while (s)
-  {
-    print " " s
-    s = substr(content, i+1, 73)
-    i = i + 73
-  }
-}
-
-# AWK program
+@include "lib/awk/icalendar.awk"
 
 BEGIN { 
   FS=":"
diff --git a/src/lib/awk/icalendar.awk b/src/lib/awk/icalendar.awk
new file mode 100644
index 0000000..c0b60cf
--- /dev/null
+++ b/src/lib/awk/icalendar.awk
@@ -0,0 +1,104 @@
+# Escape string to be used as content in iCalendar files.
+#
+# @input str: String to escape
+# @return: Escaped string
+function escape(str)
+{
+  gsub("\\\\", "\\\\", str)
+  gsub(";",    "\\;",  str)
+  gsub(",",    "\\,",  str)
+  return str
+}
+
+# Print property with its content and fold according to the iCalendar
+# specification.
+#
+# @local variables: i, s
+# @input nameparam: Property name with optional parameters
+# @input content: Escaped content
+function print_fold(nameparam, content,    i, s)
+{
+  i = 74 - length(nameparam)
+  s = substr(content, 1, i)
+  print nameparam s
+  s = substr(content, i+1, 73)
+  i = i + 73
+  while (s)
+  {
+    print " " s
+    s = substr(content, i+1, 73)
+    i = i + 73
+  }
+}
+
+# Unescape string
+#
+# @local variables: i, c, c2, res
+# @input str: String
+# @return: Unescaped string
+function unescape(str,    i, c, c2, res) {
+  for(i=1; i<=length(str);i++) {
+    c = substr(str, i, 1)
+    if (c != "\\") {
+      res = res c
+      continue
+    }
+    i++
+    c2 = substr(str, i, 1)
+    if (c2 == "n" || c2 == "N") {
+      res = res "\n"
+      continue
+    }
+    # Alternatively, c2 is "\\" or "," or ";". In each case, append res with
+    # c2. If the strings has been escaped correctly, then the character c2
+    # cannot be anything else. To be fail-safe, simply append res with c2.
+    res = res c2
+  }
+  return res
+}
+
+# Isolate content part of an iCalendar line, and unescape.
+#
+# @input str: String
+# @return: Unescaped content part
+function getcontent(str) {
+  return unescape(substr(str, index(str, ":") + 1))
+}
+
+# Time-zone aware parsing of the date/date-time entry at the current record.
+#
+# @local variables: dt
+# @return: date or date-time string that can be used in date (1)
+function parse(    dt) {
+  # Get timezone information
+  for (i=2; i<NF-1; i+=2) {
+    if ($i == "TZID") {
+      dt = "TZ=\"" $(i+1) "\" "
+      break
+    }
+  }
+  # Get date/date-time
+  return length($NF) == 8 ?
+    dt $NF :
+    dt gensub(/^([0-9]{8})T([0-9]{2})([0-9]{2})([0-9]{2})(Z)?$/, "\\1 \\2:\\3:\\4\\5", "g", $NF)
+}
+
+# Map iCalendar duration specification into the format to be used in date (1).
+#
+# @local variables: dt, dta, i, n, a, seps
+# @input duration: iCalendar duration string
+# @return: relative-date/date-time specification to be used in date (1)
+function parse_duration(duration,    dt, dta, i, n, a, seps) {
+  n = split(duration, a, /[PTWHMSD]/, seps)
+  for (i=2; i<=n; i++) {
+    if(seps[i] == "W") dta["weeks"]   = a[i]
+    if(seps[i] == "H") dta["hours"]   = a[i]
+    if(seps[i] == "M") dta["minutes"] = a[i]
+    if(seps[i] == "S") dta["seconds"] = a[i]
+    if(seps[i] == "D") dta["days"]    = a[i]
+  }
+  dt = a[1] ? a[1] : "+"
+  for (i in dta)
+    dt = dt " " dta[i] " " i
+  return dt
+}
diff --git a/src/main.sh b/src/main.sh
index 94d9fee..c60f636 100755
--- a/src/main.sh
+++ b/src/main.sh
@@ -1,1093 +1,69 @@
 #!/bin/sh
 
 set -eu
-# TODO: Make sensitive to failures. I don't want to miss appointments!
-# TODO Ensure safe use of delimiters
 
 if [ "${1:-}" = "--help" ]; then
-  echo "Usage: $0 [OPTION]"
-  echo ""
-  echo "You may specify at most one option."
-  echo "  --help                 Show this help and exit"
-  echo "  --today                Show today's appointments"
-  echo "  --yesterday            Show yesterday's appointments"
-  echo "  --tomorrow             Show tomorrow's appointments"
-  echo "  --goto                 Interactively enter date to jump to"
-  echo "  --new [date/date-time] Create new entry (today)"
-  echo "  --day [date]           Show appointments of specified day (today)"
-  echo "  --week [date]          Show week of specified date (today)"
-  echo "  --import file          Import iCalendar file"
-  echo "  --import-ni file       Import iCalendar file non-interactively"
-  echo "  --git cmd              Run git command cmd relative to calendar root"
-  echo "  --git-init             Enable the use of git"
-  echo ""
-  echo "You may also start this program with setting locale and timezone"
-  echo "information. For instance, to see and modify all of your calendar"
-  echo "entries from the perspective of Saigon, run"
-  echo "TZ='Asia/Saigon' $0"
-  echo "Likewise, you may specify the usage of Greek with"
-  echo "LC_TIME=el_GR.UTF-8 $0"
+  cat <<EOF
+Usage: $0 [OPTION]
+
+You may specify at most one of the following options:
+  --help                 Show this help and exit
+  --today                Show today's appointments
+  --yesterday            Show yesterday's appointments
+  --tomorrow             Show tomorrow's appointments
+  --goto                 Interactively enter date to jump to
+  --new [date/date-time] Create new entry (today)
+  --day [date]           Show appointments of specified day (today)
+  --week [date]          Show week of specified date (today)
+  --import file          Import iCalendar file
+  --import-ni file       Import iCalendar file non-interactively
+  --git cmd              Run git command cmd relative to calendar root
+  --git-init             Enable the use of git
+
+You may also start this program with setting locale and timezone information.
+
+For instance, to see and modify all of your calendar entries from the
+  perspective of Saigon, run
+TZ='Asia/Saigon' $0
+
+Likewise, you may see your calendar in the Greek language with
+LC_TIME=el_GR.UTF-8 $0
+EOF
   exit
 fi
 
-###
-### Helper functions
-###   err
-###
+# Theme
+. "sh/theme.sh"
 
-# err()
-# This is a helper function to print errors.
-#
-# @input $1: Error message
-err() {
-  echo "❌ $1" >/dev/tty
-}
+# Misc helper functions
+. "sh/misc.sh"
 
-###
-### preview helper functions
-###   month_previous
-###   month_next
-###   datetime_str
-###
+# Preview utilities
+. "sh/preview.sh"
 
-# month_previous()
-# Print previous month of specified input month as <month> <year>.
-#
-# @input $1: Month
-# @input $2: Year
-month_previous() {
-  month=$(echo "$1" | sed 's/^0//')
-  year=$(echo "$2" | sed 's/^0//')
-  if [ "$month" -eq 1 ]; then
-    month=12
-    year=$((year - 1))
-  else
-    month=$((month - 1))
-  fi
-  echo "$month $year"
-}
+# Preview command-line options
+. "sh/clipreview.sh"
 
-# month_next()
-# Print next month of specified input month as <month> <year>.
-#
-# @input $1: Month
-# @input $2: Year
-month_next() {
-  month=$(echo "$1" | sed 's/^0//')
-  year=$(echo "$2" | sed 's/^0//')
-  if [ "$month" -eq 12 ]; then
-    month=1
-    year=$((year + 1))
-  else
-    month=$((month + 1))
-  fi
-  echo "$month $year"
-}
+# View utilities
+. "sh/view.sh"
 
-# datetime_str()
-# Print date or datetime in a human readable form.
-#
-# @input $1:              Seconds since epoch
-# @input $2.. (optoinal): Prepend date format
-datetime_str() {
-  s="$1"
-  shift
-  t=$(date -d "@$s" +"%R")
-  dfmt="$*%e %b %Y"
-  if [ "$t" != "00:00" ]; then
-    dfmt="$dfmt %R %Z"
-  fi
-  date -d "@$s" +"$dfmt"
-}
+# Reloading command-line options
+. "sh/clireload.sh"
 
-###
-### Preview command-line options
-###   --preview-event
-###   --preview_week
-###
+# Configuration
+. "sh/config.sh"
 
-# --preview-event
-# Print preview of event and exit.
-#
-# @input $1: Line from day view containing an event
-# @req $ROOT: Path that contains the collections (see configuration)
-# @req $AWK_GET: Awk script to extract fields from iCalendar file
-# @req $AWK_ATTACHLS: Awk script to list attachments
-# @req $CAT: Program to print
-# @req colors
-if [ "${1:-}" = "--preview-event" ]; then
-  hour=$(echo "$2" | cut -d '|' -f 2)
-  start=$(echo "$2" | cut -d '|' -f 3)
-  end=$(echo "$2" | cut -d '|' -f 4)
-  fpath=$(echo "$2" | cut -d '|' -f 5 | sed "s/ /|/g")
-  if [ -n "$hour" ] && [ -n "$fpath" ]; then
-    fpath="$ROOT/$fpath"
-    start=$(datetime_str "$start" "%a ")
-    end=$(datetime_str "$end" "%a ")
-    location=$(awk -v field="LOCATION" "$AWK_GET" "$fpath")
-    status=$(awk -v field="STATUS" "$AWK_GET" "$fpath")
-    if [ "$status" = "TENTATIVE" ]; then
-      symb="🟡"
-    elif [ "$status" = "CANCELLED" ]; then
-      symb="❌"
-    fi
-    echo "📅${symb:-} ${CYAN}$start${OFF} → ${CYAN}$end${OFF}"
-    if [ -n "${location:-}" ]; then
-      echo "📍 ${CYAN}$location${OFF}"
-    fi
-    attcnt=$(awk "$AWK_ATTACHLS" "$fpath" | wc -l)
-    if [ "$attcnt" -gt 0 ]; then
-      echo "🔗 $attcnt attachments"
-    fi
-    echo ""
-    awk -v field="DESCRIPTION" "$AWK_GET" "$fpath" | $CAT
-  fi
-  exit
-fi
+# Access to awk scripts
+. "sh/awkscripts.sh"
 
-# --preview-week
-# Print preview of week.
-#
-# @input $2: Line from week view
-# @req $AWK_CALSHIFT: Awk script to make `cal` output to start on Mondays
-# @req $AWK_CALANNOT: Awk script to annotate calendar
-if [ "${1:-}" = "--preview-week" ]; then
-  sign=$(echo "$2" | cut -d '|' -f 1)
-  if [ "$sign" = "+" ]; then
-    startdate=$(echo "$2" | cut -d '|' -f 2)
-    set -- $(date -d "$startdate" +"%Y %m %d")
-    year=$1
-    month=$2
-    day=$3
-    set -- $(date -d "today" +"%Y %m %d")
-    year_cur=$1
-    month_cur=$2
-    day_cur=$3
-    # Previous months
-    set -- $(month_previous "$month" "$year")
-    month_pre="$1"
-    year_pre="$2"
-    set -- $(month_previous "$month_pre" "$year_pre")
-    month_pre2="$1"
-    year_pre2="$2"
-    # Next months
-    set -- $(month_next "$month" "$year")
-    month_nex="$1"
-    year_nex="$2"
-    set -- $(month_next "$month_nex" "$year_nex")
-    month_nex2="$1"
-    year_nex2="$2"
-    set -- $(month_next "$month_nex2" "$year_nex2")
-    month_nex3="$1"
-    year_nex3="$2"
-    # Highlight today
-    if [ "$month_pre2" -eq "$month_cur" ] && [ "$year_pre2" -eq "$year_cur" ]; then
-      var_pre2=$day_cur
-    fi
-    if [ "$month_pre" -eq "$month_cur" ] && [ "$year_pre" -eq "$year_cur" ]; then
-      var_pre=$day_cur
-    fi
-    if [ "$month" -eq "$month_cur" ] && [ "$year" -eq "$year_cur" ]; then
-      var=$day_cur
-    fi
-    if [ "$month_nex" -eq "$month_cur" ] && [ "$year_nex" -eq "$year_cur" ]; then
-      var_nex=$day_cur
-    fi
-    if [ "$month_nex2" -eq "$month_cur" ] && [ "$year_nex2" -eq "$year_cur" ]; then
-      var_nex2=$day_cur
-    fi
-    if [ "$month_nex3" -eq "$month_cur" ] && [ "$year_nex3" -eq "$year_cur" ]; then
-      var_nex3=$day_cur
-    fi
-    # show
-    (
-      cal "$month_pre2" "$year_pre2" | awk "$AWK_CALSHIFT" | awk -v cur="${var_pre2:-}" "$AWK_CALANNOT"
-      cal "$month_pre" "$year_pre" | awk "$AWK_CALSHIFT" | awk -v cur="${var_pre:-}" "$AWK_CALANNOT"
-      cal "$month" "$year" | awk "$AWK_CALSHIFT" | awk -v cur="${var:-}" -v day="$day" "$AWK_CALANNOT"
-      cal "$month_nex" "$year_nex" | awk "$AWK_CALSHIFT" | awk -v cur="${var_nex:-}" "$AWK_CALANNOT"
-      cal "$month_nex2" "$year_nex2" | awk "$AWK_CALSHIFT" | awk -v cur="${var_nex2:-}" "$AWK_CALANNOT"
-      cal "$month_nex3" "$year_nex3" | awk "$AWK_CALSHIFT" | awk -v cur="${var_nex3:-}" "$AWK_CALANNOT"
-    ) | awk '{ l[NR%8] = l[NR%8] "    " $0 } END {for (i in l) if (i>0) print l[i] }'
-  fi
-  exit
-fi
+# Functions to load calendar data
+. "sh/load.sh"
 
-###
-### View Functions
-###   __view_day
-###   __view_week
-###   __view_all
-###
+# Functions to modify iCalendar files
+. "sh/icalendar.sh"
 
-# __view_day()
-# This function prints the view for the day specified in `$DISPLAY_DATE`.
-#
-# @req $DISPLAY_DATE:      Specification of the day to show
-# @req $WEEKLY_DATA_FILE:  Filename of weekly data (see `__refresh_data` and `__load_weeks`)
-# @req $ROOT:              Path that contains the collections (see configuration)
-# @req $COLLECTION_LABELS: Mapping between collections and lables (see configuration)
-# @req $AWK_PARSE:         Parse awk script
-# @req $DAY_START:         Start time of the day (see configuration)
-# @req $DAY_END:           Start time of the day (see configuration)
-# @req $AWK_DAYVIEW:       Day-view awk script
-__view_day() {
-  weeknr=$(date -d "$DISPLAY_DATE" +"%G.%V")
-  files=$(grep "^$weeknr\ " "$WEEKLY_DATA_FILE" | cut -d " " -f 2-)
-  # Find relevant files in list of week files
-  sef=$({
-    set -- $files
-    for file in "$@"; do
-      file="$ROOT/$file"
-      awk \
-        -v collection_labels="$COLLECTION_LABELS" \
-        "$AWK_PARSE" "$file"
-    done
-  })
-  today=$(date -d "$DISPLAY_DATE" +"%D")
-  if [ -n "$sef" ]; then
-    sef=$(echo "$sef" | while IFS= read -r line; do
-      set -- $line
-      starttime="$1"
-      shift
-      endtime="$1"
-      shift
-      fpath="$(echo "$1" | sed 's/|/ /g')" # we will use | as delimiter (need to convert back!)
-      shift
-      collection="$1"
-      shift
-      status="$1"
-      shift
-      description="$(echo "$*" | sed 's/|/:/g')" # we will use | as delimiter
-      #
-      daystart=$(date -d "$today 00:00:00" +"%s")
-      dayend=$(date -d "$today 23:59:59" +"%s")
-      line=""
-      if [ "$starttime" -gt "$daystart" ] && [ "$starttime" -lt "$dayend" ]; then
-        s=$(date -d "@$starttime" +"%R")
-      elif [ "$starttime" -le "$daystart" ] && [ "$endtime" -gt "$daystart" ]; then
-        s="00:00"
-      else
-        continue
-      fi
-      if [ "$endtime" -gt "$daystart" ] && [ "$endtime" -lt "$dayend" ]; then
-        e=$(date -d "@$endtime" +"%R")
-      elif [ "$endtime" -ge "$dayend" ] && [ "$starttime" -lt "$dayend" ]; then
-        e="00:00"
-      else
-        continue
-      fi
-      echo "$s|$e|$starttime|$endtime|$fpath|$collection|$description|$status"
-    done)
-  fi
-  echo "$sef" | sort -n | awk -v today="$today" -v daystart="$DAY_START" -v dayend="$DAY_END" "$AWK_DAYVIEW"
-}
-
-# __view_week()
-# This function prints the view for the week that contains the day specified in `$DISPLAY_DATE`.
-#
-# @req $DISPLAY_DATE:      Specification of the day to show
-# @req $WEEKLY_DATA_FILE:  Filename of weekly data (see `__refresh_data` and `__load_weeks`)
-# @req $ROOT:              Path that contains the collections (see configuration)
-# @req $COLLECTION_LABELS: Mapping between collections and lables (see configuration)
-# @req $AWK_WEEKVIEW:      Week-view awk script
-# @req colors
-__view_week() {
-  weeknr=$(date -d "$DISPLAY_DATE" +"%G.%V")
-  files=$(grep "^$weeknr\ " "$WEEKLY_DATA_FILE" | cut -d " " -f 2-)
-  dayofweek=$(date -d "$DISPLAY_DATE" +"%u")
-  delta=$((1 - dayofweek))
-  startofweek=$(date -d "$DISPLAY_DATE -$delta days" +"%D")
-  # loop over files
-  sef=$({
-    set -- $files
-    for file in "$@"; do
-      file="$ROOT/$file"
-      awk \
-        -v collection_labels="$COLLECTION_LABELS" \
-        "$AWK_PARSE" "$file"
-    done
-  })
-  if [ -n "$sef" ]; then
-    sef=$(echo "$sef" | while IFS= read -r line; do
-      set -- $line
-      starttime="$1"
-      shift
-      endtime="$1"
-      shift
-      #fpath="$1"
-      shift
-      collection="$1"
-      shift
-      status="$1"
-      shift
-      if [ "$status" = "TENTATIVE" ]; then
-        symb="$FAINT$CYAN"
-      elif [ "$status" = "CANCELLED" ]; then
-        symb="$STRIKE"
-      else
-        symb=""
-      fi
-      description="${symb:-}$*$OFF"
-      for i in $(seq 0 7); do
-        daystart=$(date -d "$startofweek +$i days 00:00:00" +"%s")
-        dayend=$(date -d "$startofweek +$i days 23:59:59" +"%s")
-        if [ "$starttime" -gt "$daystart" ] && [ "$starttime" -lt "$dayend" ]; then
-          s=$(date -d "@$starttime" +"%H:%M")
-          s="$s -"
-        elif [ "$starttime" -le "$daystart" ] && [ "$endtime" -gt "$daystart" ]; then
-          s="00:00 -"
-        else
-          continue
-        fi
-        if [ "$endtime" -gt "$daystart" ] && [ "$endtime" -lt "$dayend" ]; then
-          e=$(date -d "@$endtime" +"%H:%M")
-          e="- $e"
-        elif [ "$endtime" -ge "$dayend" ] && [ "$starttime" -lt "$dayend" ]; then
-          e="- 00:00"
-        else
-          continue
-        fi
-        echo "$i $s$e >$description"
-      done
-    done)
-  fi
-  sef=$({
-    echo "$sef"
-    seq 0 7
-  } | sort -n)
-  echo "$sef" | awk -v startofweek="$startofweek" "$AWK_WEEKVIEW"
-}
-
-# __view_all()
-# This function prints all entries.
-#
-# @req $APPROX_DATA_FILE:  Filename of approximate data (see `__refresh_data` and `__load_approx_data`)
-__view_all() {
-  cat "$APPROX_DATA_FILE"
-}
-
-###
-### Command-line Arguments for reloading views
-###   --reload-day
-###   --reload-week
-###   --reload-all
-###
-
-# --reload-day
-# Reload view of specified day.
-#
-# @input $2.. (optional): Specification of day, defaults to `today`
-if [ "${1:-}" = "--reload-day" ]; then
-  shift
-  DISPLAY_DATE=${*:-today}
-  __view_day
-  exit
-fi
-
-# --reload-week
-# Reload view of the week containing the specified date.
-#
-# @input $2.. (optional): Specification of day, defaults to `today`
-if [ "${1:-}" = "--reload-week" ]; then
-  shift
-  DISPLAY_DATE=${*:-today}
-  DISPLAY_POS=$((8 - $(date -d "$DISPLAY_DATE" +"%u")))
-  __view_week
-  exit
-fi
-
-# --reload-all
-# Reload view of all entries.
-if [ "${1:-}" = "--reload-all" ]; then
-  __view_all
-  exit
-fi
-
-###
-### Load Configuration
-###   ROOT:                 Directory containing the collections
-###   COLLECTION_LABELS:    Mappings between collections and labels
-###   SYNC_CMD (optional):  Synchronization command
-###   DAY_START (optional): Hour of start of the day (defaults to 8)
-###   DAY_END (optional):   Hour of end of the day (defaults to 18)
-###   EDITOR (optional):    Your favorite editor, is usually already exported
-###   TZ (optional):        Your favorite timezone, usually system's choice
-###   LC_TIME (optional):   Your favorite locale for date and time
-###   ZI_DIR (optional):    Location of tzdata, defaults to /usr/share/zoneinfo
-###
-
-CONFIGFILE="$HOME/.config/fzf-vcal/config"
-if [ ! -f "$CONFIGFILE" ]; then
-  err "Configuration '$CONFIGFILE' not found."
-  exit 1
-fi
-# shellcheck source=/dev/null
-. "$CONFIGFILE"
-if [ -z "${ROOT:-}" ] || [ -z "${COLLECTION_LABELS:-}" ]; then
-  err "Configuration is incomplete."
-  exit 1
-fi
-SYNC_CMD=${SYNC_CMD:-echo 'Synchronization disabled'}
-DAY_START=${DAY_START:-8}
-DAY_END=${DAY_END:-18}
-ZI_DIR=${ZI_DIR:-/usr/share/zoneinfo/posix}
-if [ ! -d "$ZI_DIR" ]; then
-  err "Could not determine time-zone information"
-  exit 1
-fi
-OPEN=${OPEN:-open}
-
-###
-### Check and load required tools
-###   FZF:     Fuzzy finder `fzf``
-###   UUIDGEN: Tool `uuidgen` to generate random uids
-###   CAT:     `bat` or `batcat` or `cat`
-###   GIT:     `git` if it exists
-###
-### The presence of POSIX tools is not checked.
-###
-
-if command -v "fzf" >/dev/null; then
-  FZF="fzf --black"
-else
-  err "Did not find the command-line fuzzy finder fzf."
-  exit 1
-fi
-
-if command -v "uuidgen" >/dev/null; then
-  UUIDGEN="uuidgen"
-else
-  err "Did not find the uuidgen command."
-  exit 1
-fi
-
-if command -v "bat" >/dev/null; then
-  CAT="bat"
-elif command -v "batcat" >/dev/null; then
-  CAT="batcat"
-fi
-CAT=${CAT:+$CAT --color=always --style=numbers --language=md}
-CAT=${CAT:-cat}
-
-if command -v "git" >/dev/null && [ -d "$ROOT/.git" ]; then
-  GIT="git -C $ROOT"
-fi
-
-###
-### AWK scripts
-###   AWK_APPROX:   Generate approximate data of all files
-###   AWK_CALSHIFT: Shift calendar to start weeks on Mondays
-###   AWK_CALANNOT: Annotate calendar
-###   AWK_DAYVIEW:  Generate view of the day
-###   AWK_GET:      Print field of iCalendar file
-###   AWK_MERGE:    Generate list of weeks with associated iCalendar files
-###   AWK_NEW:      Make new iCalendar file
-###   AWK_PARSE:    Timezone aware parsing of iCalendar file for day view
-###   AWK_SET:      Set value of specific field in iCalendar file
-###   AWK_UPDATE:   Update iCalendar file
-###   AWK_WEEKVIEW: Generate view of the week
-###   AWK_ATTACHLS: List attachments
-###   AWK_ATTACHDD: Store attachment
-###   AWK_ATTACHRM: Remove attachment
-###   AWK_ATTACH:   Add attachment
-###
-
-# TODO: Complete documentation
-AWK_APPROX=$(
-  cat <<'EOF'
-@@include src/awk/approx.awk
-EOF
-)
-
-AWK_MERGE=$(
-  cat <<'EOF'
-@@include src/awk/merge.awk
-EOF
-)
-
-AWK_PARSE=$(
-  cat <<'EOF'
-@@include src/awk/parse.awk
-EOF
-)
-
-AWK_WEEKVIEW=$(
-  cat <<'EOF'
-@@include src/awk/weekview.awk
-EOF
-)
-
-AWK_DAYVIEW=$(
-  cat <<'EOF'
-@@include src/awk/dayview.awk
-EOF
-)
-
-AWK_GET=$(
-  cat <<'EOF'
-@@include src/awk/get.awk
-EOF
-)
-
-AWK_UPDATE=$(
-  cat <<'EOF'
-@@include src/awk/update.awk
-EOF
-)
-
-AWK_NEW=$(
-  cat <<'EOF'
-@@include src/awk/new.awk
-EOF
-)
-
-AWK_CALSHIFT=$(
-  cat <<'EOF'
-@@include src/awk/calshift.awk
-EOF
-)
-
-AWK_CALANNOT=$(
-  cat <<'EOF'
-@@include src/awk/calannot.awk
-EOF
-)
-
-AWK_SET=$(
-  cat <<'EOF'
-@@include src/awk/set.awk
-EOF
-)
-
-AWK_ATTACHLS=$(
-  cat <<'EOF'
-@@include src/awk/attachls.awk
-EOF
-)
-
-AWK_ATTACHDD=$(
-  cat <<'EOF'
-@@include src/awk/attachdd.awk
-EOF
-)
-
-AWK_ATTACHRM=$(
-  cat <<'EOF'
-@@include src/awk/attachrm.awk
-EOF
-)
-
-AWK_ATTACH=$(
-  cat <<'EOF'
-@@include src/awk/attach.awk
-EOF
-)
-
-###
-### Colors
-###
-#GREEN="\033[1;32m"
-#RED="\033[1;31m"
-WHITE="\033[1;97m"
-CYAN="\033[1;36m"
-STRIKE="\033[9m"
-ITALIC="\033[3m"
-FAINT="\033[2m"
-OFF="\033[m"
-
-###
-### Loading functions
-###   __load_approx_data
-###   __load_weeks
-###   __refresh_data
-###
-
-# __load_approx_data()
-# Print approximate data from iCalendar files in `$ROOT`
-# TODO: Make safe and POSIX compliant
-#
-# @req $ROOT:              Path that contains the collections (see configuration)
-# @req $COLLECTION_LABELS: Mapping between collections and lables (see configuration)
-# @req $AWK_APPROX:        Awk script for approximation
-__load_approx_data() {
-  find "$ROOT" -type f -name '*.ics' -print0 |
-    xargs -0 -P0 \
-      awk \
-      -v collection_labels="$COLLECTION_LABELS" \
-      "$AWK_APPROX"
-}
-
-# __load_weeks()
-# For every relevant week, print associated iCalendar files
-#
-# @req $APPROX_DATA_FILE:  Filename of approximate data (see `__refresh_data` and `__load_approx_data`)
-# @req $AWK_MERGE:         Merge awk script
-__load_weeks() {
-  dates=$(awk -F'|' '{ print $2; print $3 }' "$APPROX_DATA_FILE")
-  file_dates=$(mktemp)
-  echo "$dates" | date --file="/dev/stdin" +"%G|%V" >"$file_dates"
-  awk "$AWK_MERGE" "$file_dates" "$APPROX_DATA_FILE"
-  rm "$file_dates"
-}
-
-# __refresh_data()
-# Refresh approximate data and per-week data.
-#
-# This functions stores the output of `__load_approx_data` in the temporary
-# file `$APPROX_DATA_FILE` and the output of `__load_weeks` in the temporary
-# file `@WEEKLY_DATA_FILE`.
-__refresh_data() {
-  if [ -n "${APPROX_DATA_FILE:-}" ]; then
-    rm -f "$APPROX_DATA_FILE"
-  fi
-  if [ -n "${WEEKLY_DATA_FILE:-}" ]; then
-    rm -f "$WEEKLY_DATA_FILE"
-  fi
-  APPROX_DATA_FILE=$(mktemp)
-  __load_approx_data >"$APPROX_DATA_FILE"
-  WEEKLY_DATA_FILE=$(mktemp)
-  __load_weeks >"$WEEKLY_DATA_FILE"
-  trap 'rm -f "$APPROX_DATA_FILE" "$WEEKLY_DATA_FILE"' EXIT INT
-}
-
-###
-### Helper functions
-###   __datetime_human_machine
-###   __summary_for_commit
-###
-
-# __datetime_human_machine()
-# Print date or datetime in a human and machine readable form.
-#
-# @input $1: Seconds since epoch
-__datetime_human_machine() {
-  s="$1"
-  t=$(date -d "@$s" +"%R")
-  dfmt="%F"
-  if [ "$t" != "00:00" ]; then
-    dfmt="$dfmt %R"
-  fi
-  date -d "@$s" +"$dfmt"
-}
-
-# __summary_for_commit()
-# Get summary string that can be used in for git-commit messages.
-#
-# @input $1: iCalendar file path
-# @req $AWK_GET: Awk script to extract fields from iCalendar file
-__summary_for_commit() {
-  awk -v field="SUMMARY" "$AWK_GET" "$1" | tr -c -d "[:alnum:][:blank:]" | head -c 15
-}
-
-###
-### iCalendar modification wrapper
-###
-###   __edit
-###   __new
-###   __delete
-###   __import_to_collection
-###   __cancel_toggle
-###   __tentative_toggle
-###   __add_attachment
-
-# __edit()
-# Edit iCalendar file.
-#
-# @input $1: Start date/date-time
-# @input $2: End date/date-time
-# @input $3: Path to iCalendar file (relative to `$ROOT`)
-# @req $AWK_GET:    Awk script to extract fields from iCalendar file
-# @req $AWK_UPDATE: Awk script to update iCalendar file
-# @req $EDITOR:     Environment variable of your favorite editor
-__edit() {
-  start=$(__datetime_human_machine "$1")
-  end=$(__datetime_human_machine "$2")
-  fpath="$ROOT/$3"
-  location=$(awk -v field="LOCATION" "$AWK_GET" "$fpath")
-  summary=$(awk -v field="SUMMARY" "$AWK_GET" "$fpath")
-  description=$(awk -v field="DESCRIPTION" "$AWK_GET" "$fpath")
-  filetmp=$(mktemp --suffix='.md')
-  printf "::: |> %s\n::: <| %s\n" "$start" "$end" >"$filetmp"
-  if [ -n "$location" ]; then
-    printf "@ %s\n" "$location" >>"$filetmp"
-  fi
-  printf "# %s\n\n%s\n" "$summary" "$description" >>"$filetmp"
-  checksum=$(cksum "$filetmp")
-  $EDITOR "$filetmp" >/dev/tty
-
-  # Update only if changes are detected
-  if [ "$checksum" != "$(cksum "$filetmp")" ]; then
-    filenew="$filetmp.ics"
-    if awk "$AWK_UPDATE" "$filetmp" "$fpath" >"$filenew"; then
-      mv "$filenew" "$fpath"
-      if [ -n "${GIT:-}" ]; then
-        $GIT add "$fpath"
-        $GIT commit -m "Modified event '$(__summary_for_commit "$fpath") ...'" -- "$fpath"
-      fi
-      __refresh_data
-    else
-      rm -f "$filenew"
-      err "Failed to edit entry. Press <enter> to continue."
-      read -r tmp
-    fi
-  fi
-  rm "$filetmp"
-}
-
-# __new()
-# Generate new iCalendar file
-#
-# This function also sets the `$start` variable to the start of the new entry.
-# On failure, start will be empty.
-#
-# If some start has been specified and the nanoseconds are not 0, we assume
-# that the user entered "tomorrow" or something like that, and did not
-# specify the time. So, we will use the `$DAY_START` time of that date.
-# If the user specified a malformed date/date-time, we fail.
-#
-# @input $1 (optional): Date or datetime, defaults to today.
-# @req $COLLECTION_LABELS: Mapping between collections and lables (see configuration)
-# @req $UUIDGEN:           `uuidgen` command
-# @req $ROOT:              Path that contains the collections (see configuration)
-# @req $EDITOR:            Environment variable of your favorite editor
-# @req $AWK_GET:           Awk script to extract fields from iCalendar file
-# @req $AWK_new:           Awk script to generate iCalendar file
-__new() {
-  collection=$(echo "$COLLECTION_LABELS" | tr ';' '\n' | awk '/./ {print}' | $FZF --margin="30%" --no-info --delimiter='=' --with-nth=2 --accept-nth=1)
-  fpath=""
-  while [ -f "$fpath" ] || [ -z "$fpath" ]; do
-    uuid=$($UUIDGEN)
-    fpath="$ROOT/$collection/$uuid.ics"
-  done
-  d="today $DAY_START"
-  if [ -n "${1:-}" ]; then
-    d="$1"
-    if [ "$(date -d "$1" +"%N")" -ne 0 ]; then
-      d="$d $DAY_START:00"
-    fi
-  fi
-  startsec=$(date -d "$d" +"%s")
-  endsec=$((startsec + 3600))
-  start=$(__datetime_human_machine "$startsec")
-  end=$(__datetime_human_machine "$endsec")
-  filetmp=$(mktemp --suffix='.md')
-  (
-    echo "::: |> $start"
-    echo "::: <| $end"
-    echo "@ <!-- write location here, optional line -->"
-    echo "# <!-- write summary here -->"
-    echo ""
-  ) >"$filetmp"
-  checksum=$(cksum "$filetmp")
-  $EDITOR "$filetmp" >/dev/tty
-
-  # Update only if changes are detected
-  if [ "$checksum" != "$(cksum "$filetmp")" ]; then
-    filenew="$filetmp.ics"
-    if awk -v uid="$uuid" "$AWK_NEW" "$filetmp" >"$filenew"; then
-      mv "$filenew" "$fpath"
-      if [ -n "${GIT:-}" ]; then
-        $GIT add "$fpath"
-        $GIT commit -m "Added event '$(__summary_for_commit "$fpath") ...'" -- "$fpath"
-      fi
-      start=$(awk -v field="DTSTART" "$AWK_GET" "$fpath" | grep -o '[0-9]\{8\}')
-    else
-      rm -f "$filenew"
-      start=""
-      err "Failed to create new entry. Press <enter> to continue."
-      read -r tmp
-    fi
-  fi
-  rm "$filetmp"
-}
-
-# __delete()
-# Delete iCalendar file
-#
-# @input $1: Path to iCalendar file, relative to `$ROOT`
-# @req $ROOT: Path that contains the collections (see configuration)
-# @req $AWK_GET: Awk script to extract fields from iCalendar file
-__delete() {
-  fpath="$ROOT/$1"
-  summary=$(awk -v field="SUMMARY" "$AWK_GET" "$fpath")
-  while true; do
-    printf "Do you want to delete the entry with the title \"%s\"? (yes/no): " "$summary" >/dev/tty
-    read -r yn
-    case $yn in
-    "yes")
-      sfg="$(__summary_for_commit "$fpath")"
-      rm -v "$fpath"
-      if [ -n "${GIT:-}" ]; then
-        $GIT add "$fpath"
-        $GIT commit -m "Deleted event '$sfg ...'" -- "$fpath"
-      fi
-      break
-      ;;
-    "no")
-      break
-      ;;
-    *)
-      echo "Please answer \"yes\" or \"no\"." >/dev/tty
-      ;;
-    esac
-  done
-}
-
-# __import_to_collection()
-# Import iCalendar file to specified collection. The only modification made to
-# the file is setting the UID.
-#
-# @input $1: path to iCalendar file
-# @input $2: collection name
-# @req $ROOT: Path that contains the collections (see configuration)
-# @req $UUIDGEN: `uuidgen` command
-# @req $AWK_SET: Awk script to set field value
-__import_to_collection() {
-  file="$1"
-  collection="$2"
-  fpath=""
-  while [ -f "$fpath" ] || [ -z "$fpath" ]; do
-    uuid=$($UUIDGEN)
-    fpath="$ROOT/$collection/$uuid.ics"
-  done
-  filetmp=$(mktemp)
-  awk -v field="UID" -v value="$uuid" "$AWK_SET" "$file" >"$filetmp"
-  mv "$filetmp" "$fpath"
-  if [ -n "${GIT:-}" ]; then
-    $GIT add "$fpath"
-    $GIT commit -m "Imported event '$(__summary_for_commit "$fpath") ...'" -- "$fpath"
-  fi
-}
-
-# __cancel_toggle()
-# Set status of appointment to CANCELLED or CONFIRMED (toggle)
-#
-# @input $1: path to iCalendar file
-# @req $ROOT: Path that contains the collections (see configuration)
-# @req $AWK_SET: Awk script to set field value
-# @req $AWK_GET: Awk script to extract fields from iCalendar file
-__cancel_toggle() {
-  fpath="$ROOT/$1"
-  status=$(awk -v field="STATUS" "$AWK_GET" "$fpath")
-  newstatus="CANCELLED"
-  if [ "${status:-}" = "$newstatus" ]; then
-    newstatus="CONFIRMED"
-  fi
-  filetmp=$(mktemp)
-  awk -v field="STATUS" -v value="$newstatus" "$AWK_SET" "$fpath" >"$filetmp"
-  mv "$filetmp" "$fpath"
-  if [ -n "${GIT:-}" ]; then
-    $GIT add "$fpath"
-    $GIT commit -m "Event '$(__summary_for_commit "$fpath") ...' has now status $status" -- "$fpath"
-  fi
-}
-
-# __tentative_toggle
-# Toggle status flag: CONFIRMED <-> TENTATIVE
-#
-# @input $1: path to iCalendar file
-# @req $ROOT: Path that contains the collections (see configuration)
-# @req $AWK_SET: Awk script to set field value
-# @req $AWK_GET: Awk script to extract fields from iCalendar file
-__tentative_toggle() {
-  fpath="$ROOT/$1"
-  status=$(awk -v field="STATUS" "$AWK_GET" "$fpath")
-  newstatus="TENTATIVE"
-  if [ "${status:-}" = "$newstatus" ]; then
-    newstatus="CONFIRMED"
-  fi
-  filetmp=$(mktemp)
-  awk -v field="STATUS" -v value="$newstatus" "$AWK_SET" "$fpath" >"$filetmp"
-  mv "$filetmp" "$fpath"
-  if [ -n "${GIT:-}" ]; then
-    $GIT add "$fpath"
-    $GIT commit -m "Event '$(__summary_for_commit "$fpath") ...' has now status $status" -- "$fpath"
-  fi
-}
-
-# __add_attachment
-# Prepend attachment to iCalendar file
-#
-# @input $1: path to iCalendar file
-# @req $ROOT: Path that contains the collections (see configuration)
-# @req $FZF: Fuzzy finder
-# @req $AWK_ATTACH: Awk script to add attachment
-__add_attachment() {
-  fpath="$ROOT/$1"
-  sel=$(
-    $FZF --prompt="Select attachment> " \
-      --walker="file,hidden" \
-      --walker-root="$HOME" \
-      --expect="ctrl-c,ctrl-g,ctrl-q,esc"
-  )
-  key=$(echo "$sel" | head -1)
-  f=$(echo "$sel" | tail -1)
-  if [ -n "$key" ]; then
-    f=""
-  fi
-  if [ -z "$f" ] || [ ! -f "$f" ]; then
-    return
-  fi
-  filename=$(basename "$f")
-  mime=$(file -b -i "$f" | cut -d ';' -f 1)
-  if [ -z "$mime" ]; then
-    mime="application/octet-stream"
-  fi
-  fenc=$(mktemp)
-  base64 "$f" >"$fenc"
-  filetmp=$(mktemp)
-  awk -v file="$fenc" -v mime="$mime" -v filename="$filename" "$AWK_ATTACH" "$fpath" >"$filetmp"
-  mv "$filetmp" "$fpath"
-  if [ -n "${GIT:-}" ]; then
-    $GIT add "$fpath"
-    $GIT commit -m "Added attachment to '$(__summary_for_commit "$fpath") ...'" -- "$fpath"
-  fi
-  rm "$fenc"
-}
-
-###
-### Extra command-line options
-###   --import-ni
-###   --import
-###   --git
-###   --git-init
-###
-
-# --import-ni
-# Import iCalendar file noninteractively
-#
-# @input $2: Absolute path to iCalendar file
-# @input $3: Collection
-# @req $COLLECTION_LABELS: Mapping between collections and labels (see configuration)
-# @req $ROOT: Path that contains the collections (see configuration)
-# @return: On success, returns 0, otherwise 1
-if [ "${1:-}" = "--import-ni" ]; then
-  shift
-  file="${1:-}"
-  collection="${2:-}"
-  if [ ! -f "$file" ]; then
-    err "File \"$file\" does not exist"
-    exit 1
-  fi
-  for c in $(echo "$COLLECTION_LABELS" | sed "s|=[^;]*;| |g"); do
-    if [ "$collection" = "$c" ]; then
-      cexists="yes"
-      break
-    fi
-  done
-  if [ -n "${cexists:-}" ] && [ -d "$ROOT/$collection" ]; then
-    __import_to_collection "$file" "$collection"
-  else
-    err "Collection \"$collection\" does not exist"
-    exit 1
-  fi
-  exit
-fi
-
-# --import
-# Import iCalendar file.
-#
-# @input $2: Absolute path to iCalendar file
-# @req $COLLECTION_LABELS: Mapping between collections and lables (see configuration)
-# @req $AWK_PARSE: Parse awk script
-# @req $AWK_GET: Awk script to extract fields from iCalendar file
-# @req $FZF: `fzf` command
-# @req $CAT: Program to print
-# @return: On success, returns 0, otherwise 1
-if [ "${1:-}" = "--import" ]; then
-  shift
-  file="${1:-}"
-  if [ ! -f "$file" ]; then
-    err "File \"$file\" does not exist"
-    return 1
-  fi
-  line=$(awk \
-    -v collection_labels="$COLLECTION_LABELS" \
-    "$AWK_PARSE" "$file")
-  set -- $line
-  startsec="${1:-}"
-  endsec="${2:-}"
-  if [ -z "$line" ] || [ -z "$startsec" ] || [ -z "$endsec" ]; then
-    err "File \"$file\" does not look like an iCalendar file containing an event"
-    return 1
-  fi
-  start=$(__datetime_human_machine "$startsec")
-  end=$(__datetime_human_machine "$endsec")
-  location=$(awk -v field="LOCATION" "$AWK_GET" "$file")
-  summary=$(awk -v field="SUMMARY" "$AWK_GET" "$file")
-  description=$(awk -v field="DESCRIPTION" "$AWK_GET" "$file")
-  filetmp=$(mktemp --suffix='.md')
-  (
-    echo "::: |> $start"
-    echo "::: <| $end"
-  ) >"$filetmp"
-  if [ -n "$location" ]; then
-    echo "@ $location" >>"$filetmp"
-  fi
-  (
-    echo "# $summary"
-    echo ""
-    echo "$description"
-  ) >>"$filetmp"
-  $CAT "$filetmp" >/dev/tty
-  while true; do
-    printf "Do you want to import this entry? (yes/no): " >/dev/tty
-    read -r yn
-    case $yn in
-    "yes")
-      collection=$(echo "$COLLECTION_LABELS" | tr ';' '\n' | awk '/./ {print}' | $FZF --margin="30%" --no-info --delimiter='=' --with-nth=2 --accept-nth=1)
-      if [ -z "$collection" ]; then
-        exit
-      fi
-      __import_to_collection "$file" "$collection"
-      break
-      ;;
-    "no")
-      break
-      ;;
-    *)
-      echo "Please answer \"yes\" or \"no\"." >/dev/tty
-      ;;
-    esac
-  done
-  rm -f "$filetmp"
-  exit
-fi
-
-# --git
-# Run git command
-#
-# @input $2..: Git command
-# @req $GIT: git command with `-C` flag set
-# @return: On success, returns 0, otherwise 1
-if [ "${1:-}" = "--git" ]; then
-  if [ -z "${GIT:-}" ]; then
-    err "Git not supported, run \`$0 --git-init\` first"
-    return 1
-  fi
-  shift
-  $GIT "$@"
-  exit
-fi
-#
-# --git-init
-# Enable the ues of git
-#
-# @return: On success, returns 0, otherwise 1
-if [ "${1:-}" = "--git-init" ]; then
-  if [ -n "${GIT:-}" ]; then
-    err "Git already enabled"
-    return 1
-  fi
-  if ! command -v "git" >/dev/null; then
-    err "Git command not found"
-    return 1
-  fi
-  git -C "$ROOT" init
-  git -C "$ROOT" add -A
-  git -C "$ROOT" commit -m 'Initial commit: Start git tracking'
-  exit
-fi
+# Extra, run-and-exit command-line options
+. "sh/cliextra.sh"
 
 ### Start
 __refresh_data
diff --git a/src/sh/awkscripts.sh b/src/sh/awkscripts.sh
new file mode 100644
index 0000000..c429c65
--- /dev/null
+++ b/src/sh/awkscripts.sh
@@ -0,0 +1,106 @@
+# AWK scripts
+# - AWK_APPROX:   Generate approximate data of all files
+# - AWK_CALSHIFT: Shift calendar to start weeks on Mondays
+# - AWK_CALANNOT: Annotate calendar
+# - AWK_DAYVIEW:  Generate view of the day
+# - AWK_GET:      Print field of iCalendar file
+# - AWK_MERGE:    Generate list of weeks with associated iCalendar files
+# - AWK_NEW:      Make new iCalendar file
+# - AWK_PARSE:    Timezone aware parsing of iCalendar file for day view
+# - AWK_SET:      Set value of specific field in iCalendar file
+# - AWK_UPDATE:   Update iCalendar file
+# - AWK_WEEKVIEW: Generate view of the week
+# - AWK_ATTACHLS: List attachments
+# - AWK_ATTACHDD: Store attachment
+# - AWK_ATTACHRM: Remove attachment
+# - AWK_ATTACH:   Add attachment
+
+AWK_APPROX=$(
+  cat <<'EOF'
+@@include awk/approx.awk
+EOF
+)
+
+AWK_MERGE=$(
+  cat <<'EOF'
+@@include awk/merge.awk
+EOF
+)
+
+AWK_PARSE=$(
+  cat <<'EOF'
+@@include awk/parse.awk
+EOF
+)
+
+AWK_WEEKVIEW=$(
+  cat <<'EOF'
+@@include awk/weekview.awk
+EOF
+)
+
+AWK_DAYVIEW=$(
+  cat <<'EOF'
+@@include awk/dayview.awk
+EOF
+)
+
+AWK_GET=$(
+  cat <<'EOF'
+@@include awk/get.awk
+EOF
+)
+
+AWK_UPDATE=$(
+  cat <<'EOF'
+@@include awk/update.awk
+EOF
+)
+
+AWK_NEW=$(
+  cat <<'EOF'
+@@include awk/new.awk
+EOF
+)
+
+AWK_CALSHIFT=$(
+  cat <<'EOF'
+@@include awk/calshift.awk
+EOF
+)
+
+AWK_CALANNOT=$(
+  cat <<'EOF'
+@@include awk/calannot.awk
+EOF
+)
+
+AWK_SET=$(
+  cat <<'EOF'
+@@include awk/set.awk
+EOF
+)
+
+AWK_ATTACHLS=$(
+  cat <<'EOF'
+@@include awk/attachls.awk
+EOF
+)
+
+AWK_ATTACHDD=$(
+  cat <<'EOF'
+@@include awk/attachdd.awk
+EOF
+)
+
+AWK_ATTACHRM=$(
+  cat <<'EOF'
+@@include awk/attachrm.awk
+EOF
+)
+
+AWK_ATTACH=$(
+  cat <<'EOF'
+@@include awk/attach.awk
+EOF
+)
diff --git a/src/sh/cliextra.sh b/src/sh/cliextra.sh
new file mode 100644
index 0000000..49818f9
--- /dev/null
+++ b/src/sh/cliextra.sh
@@ -0,0 +1,129 @@
+# Extra command-line options
+# - --import-ni
+# - --import
+# - --git
+# - --git-init
+
+# Import iCalendar file noninteractively
+#
+# @input $2: Absolute path to iCalendar file
+# @input $3: Collection
+# @return: On success, returns 0, otherwise 1
+if [ "${1:-}" = "--import-ni" ]; then
+  shift
+  file="${1:-}"
+  collection="${2:-}"
+  if [ ! -f "$file" ]; then
+    err "File \"$file\" does not exist"
+    exit 1
+  fi
+  for c in $(echo "$COLLECTION_LABELS" | sed "s|=[^;]*;| |g"); do
+    if [ "$collection" = "$c" ]; then
+      cexists="yes"
+      break
+    fi
+  done
+  if [ -n "${cexists:-}" ] && [ -d "$ROOT/$collection" ]; then
+    __import_to_collection "$file" "$collection"
+  else
+    err "Collection \"$collection\" does not exist"
+    exit 1
+  fi
+  exit
+fi
+
+# Import iCalendar file.
+#
+# @input $2: Absolute path to iCalendar file
+# @return: On success, returns 0, otherwise 1
+if [ "${1:-}" = "--import" ]; then
+  shift
+  file="${1:-}"
+  if [ ! -f "$file" ]; then
+    err "File \"$file\" does not exist"
+    return 1
+  fi
+  line=$(awk \
+    -v collection_labels="$COLLECTION_LABELS" \
+    "$AWK_PARSE" "$file")
+  set -- $line
+  startsec="${1:-}"
+  endsec="${2:-}"
+  if [ -z "$line" ] || [ -z "$startsec" ] || [ -z "$endsec" ]; then
+    err "File \"$file\" does not look like an iCalendar file containing an event"
+    return 1
+  fi
+  start=$(__datetime_human_machine "$startsec")
+  end=$(__datetime_human_machine "$endsec")
+  location=$(awk -v field="LOCATION" "$AWK_GET" "$file")
+  summary=$(awk -v field="SUMMARY" "$AWK_GET" "$file")
+  description=$(awk -v field="DESCRIPTION" "$AWK_GET" "$file")
+  filetmp=$(mktemp --suffix='.md')
+  (
+    echo "::: |> $start"
+    echo "::: <| $end"
+  ) >"$filetmp"
+  if [ -n "$location" ]; then
+    echo "@ $location" >>"$filetmp"
+  fi
+  (
+    echo "# $summary"
+    echo ""
+    echo "$description"
+  ) >>"$filetmp"
+  $CAT "$filetmp" >/dev/tty
+  while true; do
+    printf "Do you want to import this entry? (yes/no): " >/dev/tty
+    read -r yn
+    case $yn in
+    "yes")
+      collection=$(echo "$COLLECTION_LABELS" | tr ';' '\n' | awk '/./ {print}' | $FZF --margin="30%" --no-info --delimiter='=' --with-nth=2 --accept-nth=1)
+      if [ -z "$collection" ]; then
+        exit
+      fi
+      __import_to_collection "$file" "$collection"
+      break
+      ;;
+    "no")
+      break
+      ;;
+    *)
+      echo "Please answer \"yes\" or \"no\"." >/dev/tty
+      ;;
+    esac
+  done
+  rm -f "$filetmp"
+  exit
+fi
+
+# Run git command
+#
+# @input $2..: Git command
+# @return: On success, returns 0, otherwise 1
+if [ "${1:-}" = "--git" ]; then
+  if [ -z "${GIT:-}" ]; then
+    err "Git not supported, run \`$0 --git-init\` first"
+    return 1
+  fi
+  shift
+  $GIT "$@"
+  exit
+fi
+
+# Enable the ues of git
+#
+# @return: On success, returns 0, otherwise 1
+if [ "${1:-}" = "--git-init" ]; then
+  if [ -n "${GIT:-}" ]; then
+    err "Git already enabled"
+    return 1
+  fi
+  if ! command -v "git" >/dev/null; then
+    err "Git command not found"
+    return 1
+  fi
+  git -C "$ROOT" init
+  git -C "$ROOT" add -A
+  git -C "$ROOT" commit -m 'Initial commit: Start git tracking'
+  exit
+fi
diff --git a/src/sh/clipreview.sh b/src/sh/clipreview.sh
new file mode 100644
index 0000000..f5036ea
--- /dev/null
+++ b/src/sh/clipreview.sh
@@ -0,0 +1,100 @@
+# Preview command-line options
+# - --preview-event
+# - --preview_week
+
+# Print preview of event and exit.
+#
+# @input $2: Line from day view containing an event
+if [ "${1:-}" = "--preview-event" ]; then
+  hour=$(echo "$2" | cut -d '|' -f 2)
+  start=$(echo "$2" | cut -d '|' -f 3)
+  end=$(echo "$2" | cut -d '|' -f 4)
+  fpath=$(echo "$2" | cut -d '|' -f 5 | sed "s/ /|/g")
+  if [ -n "$hour" ] && [ -n "$fpath" ]; then
+    fpath="$ROOT/$fpath"
+    start=$(datetime_str "$start" "%a ")
+    end=$(datetime_str "$end" "%a ")
+    location=$(awk -v field="LOCATION" "$AWK_GET" "$fpath")
+    status=$(awk -v field="STATUS" "$AWK_GET" "$fpath")
+    if [ "$status" = "TENTATIVE" ]; then
+      symb="🟡"
+    elif [ "$status" = "CANCELLED" ]; then
+      symb="❌"
+    fi
+    echo "📅${symb:-} ${CYAN}$start${OFF} → ${CYAN}$end${OFF}"
+    if [ -n "${location:-}" ]; then
+      echo "📍 ${CYAN}$location${OFF}"
+    fi
+    attcnt=$(awk "$AWK_ATTACHLS" "$fpath" | wc -l)
+    if [ "$attcnt" -gt 0 ]; then
+      echo "🔗 $attcnt attachments"
+    fi
+    echo ""
+    awk -v field="DESCRIPTION" "$AWK_GET" "$fpath" | $CAT
+  fi
+  exit
+fi
+
+# Print preview of week.
+#
+# @input $2: Line from week view
+if [ "${1:-}" = "--preview-week" ]; then
+  sign=$(echo "$2" | cut -d '|' -f 1)
+  if [ "$sign" = "+" ]; then
+    startdate=$(echo "$2" | cut -d '|' -f 2)
+    set -- $(date -d "$startdate" +"%Y %m %d")
+    year=$1
+    month=$2
+    day=$3
+    set -- $(date -d "today" +"%Y %m %d")
+    year_cur=$1
+    month_cur=$2
+    day_cur=$3
+    # Previous months
+    set -- $(month_previous "$month" "$year")
+    month_pre="$1"
+    year_pre="$2"
+    set -- $(month_previous "$month_pre" "$year_pre")
+    month_pre2="$1"
+    year_pre2="$2"
+    # Next months
+    set -- $(month_next "$month" "$year")
+    month_nex="$1"
+    year_nex="$2"
+    set -- $(month_next "$month_nex" "$year_nex")
+    month_nex2="$1"
+    year_nex2="$2"
+    set -- $(month_next "$month_nex2" "$year_nex2")
+    month_nex3="$1"
+    year_nex3="$2"
+    # Highlight today
+    if [ "$month_pre2" -eq "$month_cur" ] && [ "$year_pre2" -eq "$year_cur" ]; then
+      var_pre2=$day_cur
+    fi
+    if [ "$month_pre" -eq "$month_cur" ] && [ "$year_pre" -eq "$year_cur" ]; then
+      var_pre=$day_cur
+    fi
+    if [ "$month" -eq "$month_cur" ] && [ "$year" -eq "$year_cur" ]; then
+      var=$day_cur
+    fi
+    if [ "$month_nex" -eq "$month_cur" ] && [ "$year_nex" -eq "$year_cur" ]; then
+      var_nex=$day_cur
+    fi
+    if [ "$month_nex2" -eq "$month_cur" ] && [ "$year_nex2" -eq "$year_cur" ]; then
+      var_nex2=$day_cur
+    fi
+    if [ "$month_nex3" -eq "$month_cur" ] && [ "$year_nex3" -eq "$year_cur" ]; then
+      var_nex3=$day_cur
+    fi
+    # show
+    (
+      cal "$month_pre2" "$year_pre2" | awk "$AWK_CALSHIFT" | awk -v cur="${var_pre2:-}" "$AWK_CALANNOT"
+      cal "$month_pre" "$year_pre" | awk "$AWK_CALSHIFT" | awk -v cur="${var_pre:-}" "$AWK_CALANNOT"
+      cal "$month" "$year" | awk "$AWK_CALSHIFT" | awk -v cur="${var:-}" -v day="$day" "$AWK_CALANNOT"
+      cal "$month_nex" "$year_nex" | awk "$AWK_CALSHIFT" | awk -v cur="${var_nex:-}" "$AWK_CALANNOT"
+      cal "$month_nex2" "$year_nex2" | awk "$AWK_CALSHIFT" | awk -v cur="${var_nex2:-}" "$AWK_CALANNOT"
+      cal "$month_nex3" "$year_nex3" | awk "$AWK_CALSHIFT" | awk -v cur="${var_nex3:-}" "$AWK_CALANNOT"
+    ) | awk '{ l[NR%8] = l[NR%8] "    " $0 } END {for (i in l) if (i>0) print l[i] }'
+  fi
+  exit
+fi
diff --git a/src/sh/clireload.sh b/src/sh/clireload.sh
new file mode 100644
index 0000000..9bc1131
--- /dev/null
+++ b/src/sh/clireload.sh
@@ -0,0 +1,31 @@
+# Command-line Arguments for reloading views
+# - --reload-day
+# - --reload-week
+# - --reload-all
+
+# Reload view of specified day.
+#
+# @input $2.. (optional): Specification of day, defaults to `today`
+if [ "${1:-}" = "--reload-day" ]; then
+  shift
+  DISPLAY_DATE=${*:-today}
+  __view_day
+  exit
+fi
+
+# Reload view of the week containing the specified date.
+#
+# @input $2.. (optional): Specification of day, defaults to `today`
+if [ "${1:-}" = "--reload-week" ]; then
+  shift
+  DISPLAY_DATE=${*:-today}
+  DISPLAY_POS=$((8 - $(date -d "$DISPLAY_DATE" +"%u")))
+  __view_week
+  exit
+fi
+
+# Reload view of all entries.
+if [ "${1:-}" = "--reload-all" ]; then
+  __view_all
+  exit
+fi
diff --git a/src/sh/config.sh b/src/sh/config.sh
new file mode 100644
index 0000000..56934a5
--- /dev/null
+++ b/src/sh/config.sh
@@ -0,0 +1,65 @@
+# Load Configuration
+# - ROOT:                 Directory containing the collections
+# - COLLECTION_LABELS:    Mappings between collections and labels
+# - SYNC_CMD (optional):  Synchronization command
+# - DAY_START (optional): Hour of start of the day (defaults to 8)
+# - DAY_END (optional):   Hour of end of the day (defaults to 18)
+# - EDITOR (optional):    Your favorite editor, is usually already exported
+# - TZ (optional):        Your favorite timezone, usually system's choice
+# - LC_TIME (optional):   Your favorite locale for date and time
+# - ZI_DIR (optional):    Location of tzdata, defaults to /usr/share/zoneinfo
+
+CONFIGFILE="$HOME/.config/fzf-vcal/config"
+if [ ! -f "$CONFIGFILE" ]; then
+  err "Configuration '$CONFIGFILE' not found."
+  exit 1
+fi
+# shellcheck source=/dev/null
+. "$CONFIGFILE"
+if [ -z "${ROOT:-}" ] || [ -z "${COLLECTION_LABELS:-}" ]; then
+  err "Configuration is incomplete."
+  exit 1
+fi
+SYNC_CMD=${SYNC_CMD:-echo 'Synchronization disabled'}
+DAY_START=${DAY_START:-8}
+DAY_END=${DAY_END:-18}
+ZI_DIR=${ZI_DIR:-/usr/share/zoneinfo/posix}
+if [ ! -d "$ZI_DIR" ]; then
+  err "Could not determine time-zone information"
+  exit 1
+fi
+OPEN=${OPEN:-open}
+
+# Check and load required tools
+# - FZF:     Fuzzy finder `fzf``
+# - UUIDGEN: Tool `uuidgen` to generate random uids
+# - CAT:     `bat` or `batcat` or `cat`
+# - GIT:     `git` if it exists
+#
+# The presence of POSIX tools is not checked.
+
+if command -v "fzf" >/dev/null; then
+  FZF="fzf --black"
+else
+  err "Did not find the command-line fuzzy finder fzf."
+  exit 1
+fi
+
+if command -v "uuidgen" >/dev/null; then
+  UUIDGEN="uuidgen"
+else
+  err "Did not find the uuidgen command."
+  exit 1
+fi
+
+if command -v "bat" >/dev/null; then
+  CAT="bat"
+elif command -v "batcat" >/dev/null; then
+  CAT="batcat"
+fi
+CAT=${CAT:+$CAT --color=always --style=numbers --language=md}
+CAT=${CAT:-cat}
+
+if command -v "git" >/dev/null && [ -d "$ROOT/.git" ]; then
+  GIT="git -C $ROOT"
+fi
diff --git a/src/sh/icalendar.sh b/src/sh/icalendar.sh
new file mode 100644
index 0000000..35f2657
--- /dev/null
+++ b/src/sh/icalendar.sh
@@ -0,0 +1,256 @@
+# iCalendar modification wrapper
+# - __edit
+# - __new
+# - __delete
+# - __import_to_collection
+# - __cancel_toggle
+# - __tentative_toggle
+# - __add_attachment
+
+# Edit iCalendar file.
+#
+# @input $1: Start date/date-time
+# @input $2: End date/date-time
+# @input $3: Path to iCalendar file (relative to `$ROOT`)
+# @req $AWK_GET:    Awk script to extract fields from iCalendar file
+# @req $AWK_UPDATE: Awk script to update iCalendar file
+# @req $EDITOR:     Environment variable of your favorite editor
+__edit() {
+  start=$(__datetime_human_machine "$1")
+  end=$(__datetime_human_machine "$2")
+  fpath="$ROOT/$3"
+  location=$(awk -v field="LOCATION" "$AWK_GET" "$fpath")
+  summary=$(awk -v field="SUMMARY" "$AWK_GET" "$fpath")
+  description=$(awk -v field="DESCRIPTION" "$AWK_GET" "$fpath")
+  filetmp=$(mktemp --suffix='.md')
+  printf "::: |> %s\n::: <| %s\n" "$start" "$end" >"$filetmp"
+  if [ -n "$location" ]; then
+    printf "@ %s\n" "$location" >>"$filetmp"
+  fi
+  printf "# %s\n\n%s\n" "$summary" "$description" >>"$filetmp"
+  checksum=$(cksum "$filetmp")
+  $EDITOR "$filetmp" >/dev/tty
+
+  # Update only if changes are detected
+  if [ "$checksum" != "$(cksum "$filetmp")" ]; then
+    filenew="$filetmp.ics"
+    if awk "$AWK_UPDATE" "$filetmp" "$fpath" >"$filenew"; then
+      mv "$filenew" "$fpath"
+      if [ -n "${GIT:-}" ]; then
+        $GIT add "$fpath"
+        $GIT commit -m "Modified event '$(__summary_for_commit "$fpath") ...'" -- "$fpath"
+      fi
+      __refresh_data
+    else
+      rm -f "$filenew"
+      err "Failed to edit entry. Press <enter> to continue."
+      read -r tmp
+    fi
+  fi
+  rm "$filetmp"
+}
+
+# Generate new iCalendar file
+#
+# This function also sets the `$start` variable to the start of the new entry.
+# On failure, start will be empty.
+#
+# If some start has been specified and the nanoseconds are not 0, we assume
+# that the user entered "tomorrow" or something like that, and did not
+# specify the time. So, we will use the `$DAY_START` time of that date.
+# If the user specified a malformed date/date-time, we fail.
+#
+# @input $1 (optional): Date or datetime, defaults to today.
+# @req $COLLECTION_LABELS: Mapping between collections and lables (see configuration)
+# @req $UUIDGEN:           `uuidgen` command
+# @req $ROOT:              Path that contains the collections (see configuration)
+# @req $EDITOR:            Environment variable of your favorite editor
+# @req $AWK_GET:           Awk script to extract fields from iCalendar file
+# @req $AWK_new:           Awk script to generate iCalendar file
+__new() {
+  collection=$(echo "$COLLECTION_LABELS" | tr ';' '\n' | awk '/./ {print}' | $FZF --margin="30%" --no-info --delimiter='=' --with-nth=2 --accept-nth=1)
+  fpath=""
+  while [ -f "$fpath" ] || [ -z "$fpath" ]; do
+    uuid=$($UUIDGEN)
+    fpath="$ROOT/$collection/$uuid.ics"
+  done
+  d="today $DAY_START"
+  if [ -n "${1:-}" ]; then
+    d="$1"
+    if [ "$(date -d "$1" +"%N")" -ne 0 ]; then
+      d="$d $DAY_START:00"
+    fi
+  fi
+  startsec=$(date -d "$d" +"%s")
+  endsec=$((startsec + 3600))
+  start=$(__datetime_human_machine "$startsec")
+  end=$(__datetime_human_machine "$endsec")
+  filetmp=$(mktemp --suffix='.md')
+  (
+    echo "::: |> $start"
+    echo "::: <| $end"
+    echo "@ <!-- write location here, optional line -->"
+    echo "# <!-- write summary here -->"
+    echo ""
+  ) >"$filetmp"
+  checksum=$(cksum "$filetmp")
+  $EDITOR "$filetmp" >/dev/tty
+
+  # Update only if changes are detected
+  if [ "$checksum" != "$(cksum "$filetmp")" ]; then
+    filenew="$filetmp.ics"
+    if awk -v uid="$uuid" "$AWK_NEW" "$filetmp" >"$filenew"; then
+      mv "$filenew" "$fpath"
+      if [ -n "${GIT:-}" ]; then
+        $GIT add "$fpath"
+        $GIT commit -m "Added event '$(__summary_for_commit "$fpath") ...'" -- "$fpath"
+      fi
+      start=$(awk -v field="DTSTART" "$AWK_GET" "$fpath" | grep -o '[0-9]\{8\}')
+    else
+      rm -f "$filenew"
+      start=""
+      err "Failed to create new entry. Press <enter> to continue."
+      read -r tmp
+    fi
+  fi
+  rm "$filetmp"
+}
+
+# Delete iCalendar file
+#
+# @input $1: Path to iCalendar file, relative to `$ROOT`
+# @req $ROOT: Path that contains the collections (see configuration)
+# @req $AWK_GET: Awk script to extract fields from iCalendar file
+__delete() {
+  fpath="$ROOT/$1"
+  summary=$(awk -v field="SUMMARY" "$AWK_GET" "$fpath")
+  while true; do
+    printf "Do you want to delete the entry with the title \"%s\"? (yes/no): " "$summary" >/dev/tty
+    read -r yn
+    case $yn in
+    "yes")
+      sfg="$(__summary_for_commit "$fpath")"
+      rm -v "$fpath"
+      if [ -n "${GIT:-}" ]; then
+        $GIT add "$fpath"
+        $GIT commit -m "Deleted event '$sfg ...'" -- "$fpath"
+      fi
+      break
+      ;;
+    "no")
+      break
+      ;;
+    *)
+      echo "Please answer \"yes\" or \"no\"." >/dev/tty
+      ;;
+    esac
+  done
+}
+
+# Import iCalendar file to specified collection. The only modification made to
+# the file is setting the UID.
+#
+# @input $1: path to iCalendar file
+# @input $2: collection name
+# @req $ROOT: Path that contains the collections (see configuration)
+# @req $UUIDGEN: `uuidgen` command
+# @req $AWK_SET: Awk script to set field value
+__import_to_collection() {
+  file="$1"
+  collection="$2"
+  fpath=""
+  while [ -f "$fpath" ] || [ -z "$fpath" ]; do
+    uuid=$($UUIDGEN)
+    fpath="$ROOT/$collection/$uuid.ics"
+  done
+  filetmp=$(mktemp)
+  awk -v field="UID" -v value="$uuid" "$AWK_SET" "$file" >"$filetmp"
+  mv "$filetmp" "$fpath"
+  if [ -n "${GIT:-}" ]; then
+    $GIT add "$fpath"
+    $GIT commit -m "Imported event '$(__summary_for_commit "$fpath") ...'" -- "$fpath"
+  fi
+}
+
+# Set status of appointment to CANCELLED or CONFIRMED (toggle)
+#
+# @input $1: path to iCalendar file
+# @req $ROOT: Path that contains the collections (see configuration)
+# @req $AWK_SET: Awk script to set field value
+# @req $AWK_GET: Awk script to extract fields from iCalendar file
+__cancel_toggle() {
+  fpath="$ROOT/$1"
+  status=$(awk -v field="STATUS" "$AWK_GET" "$fpath")
+  newstatus="CANCELLED"
+  if [ "${status:-}" = "$newstatus" ]; then
+    newstatus="CONFIRMED"
+  fi
+  filetmp=$(mktemp)
+  awk -v field="STATUS" -v value="$newstatus" "$AWK_SET" "$fpath" >"$filetmp"
+  mv "$filetmp" "$fpath"
+  if [ -n "${GIT:-}" ]; then
+    $GIT add "$fpath"
+    $GIT commit -m "Event '$(__summary_for_commit "$fpath") ...' has now status $status" -- "$fpath"
+  fi
+}
+
+# Toggle status flag: CONFIRMED <-> TENTATIVE
+#
+# @input $1: path to iCalendar file
+# @req $ROOT: Path that contains the collections (see configuration)
+# @req $AWK_SET: Awk script to set field value
+# @req $AWK_GET: Awk script to extract fields from iCalendar file
+__tentative_toggle() {
+  fpath="$ROOT/$1"
+  status=$(awk -v field="STATUS" "$AWK_GET" "$fpath")
+  newstatus="TENTATIVE"
+  if [ "${status:-}" = "$newstatus" ]; then
+    newstatus="CONFIRMED"
+  fi
+  filetmp=$(mktemp)
+  awk -v field="STATUS" -v value="$newstatus" "$AWK_SET" "$fpath" >"$filetmp"
+  mv "$filetmp" "$fpath"
+  if [ -n "${GIT:-}" ]; then
+    $GIT add "$fpath"
+    $GIT commit -m "Event '$(__summary_for_commit "$fpath") ...' has now status $status" -- "$fpath"
+  fi
+}
+
+# Prepend attachment to iCalendar file
+#
+# @input $1: path to iCalendar file
+# @req $ROOT: Path that contains the collections (see configuration)
+# @req $FZF: Fuzzy finder
+# @req $AWK_ATTACH: Awk script to add attachment
+__add_attachment() {
+  fpath="$ROOT/$1"
+  sel=$(
+    $FZF --prompt="Select attachment> " \
+      --walker="file,hidden" \
+      --walker-root="$HOME" \
+      --expect="ctrl-c,ctrl-g,ctrl-q,esc"
+  )
+  key=$(echo "$sel" | head -1)
+  f=$(echo "$sel" | tail -1)
+  if [ -n "$key" ]; then
+    f=""
+  fi
+  if [ -z "$f" ] || [ ! -f "$f" ]; then
+    return
+  fi
+  filename=$(basename "$f")
+  mime=$(file -b -i "$f" | cut -d ';' -f 1)
+  if [ -z "$mime" ]; then
+    mime="application/octet-stream"
+  fi
+  fenc=$(mktemp)
+  base64 "$f" >"$fenc"
+  filetmp=$(mktemp)
+  awk -v file="$fenc" -v mime="$mime" -v filename="$filename" "$AWK_ATTACH" "$fpath" >"$filetmp"
+  mv "$filetmp" "$fpath"
+  if [ -n "${GIT:-}" ]; then
+    $GIT add "$fpath"
+    $GIT commit -m "Added attachment to '$(__summary_for_commit "$fpath") ...'" -- "$fpath"
+  fi
+  rm "$fenc"
+}
diff --git a/src/sh/load.sh b/src/sh/load.sh
new file mode 100644
index 0000000..33cded1
--- /dev/null
+++ b/src/sh/load.sh
@@ -0,0 +1,41 @@
+# Loading functions
+# - __load_approx_data
+# - __load_weeks
+# - __refresh_data
+
+# Print approximate data from iCalendar files in `$ROOT`
+__load_approx_data() {
+  find "$ROOT" -type f -name '*.ics' -print0 |
+    xargs -0 -P0 \
+      awk \
+      -v collection_labels="$COLLECTION_LABELS" \
+      "$AWK_APPROX"
+}
+
+# For every relevant week, print associated iCalendar files
+__load_weeks() {
+  dates=$(awk -F'|' '{ print $2; print $3 }' "$APPROX_DATA_FILE")
+  file_dates=$(mktemp)
+  echo "$dates" | date --file="/dev/stdin" +"%G|%V" >"$file_dates"
+  awk "$AWK_MERGE" "$file_dates" "$APPROX_DATA_FILE"
+  rm "$file_dates"
+}
+
+# Refresh approximate data and per-week data.
+#
+# This functions stores the output of `__load_approx_data` in the temporary
+# file `$APPROX_DATA_FILE` and the output of `__load_weeks` in the temporary
+# file `@WEEKLY_DATA_FILE`.
+__refresh_data() {
+  if [ -n "${APPROX_DATA_FILE:-}" ]; then
+    rm -f "$APPROX_DATA_FILE"
+  fi
+  if [ -n "${WEEKLY_DATA_FILE:-}" ]; then
+    rm -f "$WEEKLY_DATA_FILE"
+  fi
+  APPROX_DATA_FILE=$(mktemp)
+  __load_approx_data >"$APPROX_DATA_FILE"
+  WEEKLY_DATA_FILE=$(mktemp)
+  __load_weeks >"$WEEKLY_DATA_FILE"
+  trap 'rm -f "$APPROX_DATA_FILE" "$WEEKLY_DATA_FILE"' EXIT INT
+}
diff --git a/src/sh/misc.sh b/src/sh/misc.sh
new file mode 100644
index 0000000..c162ffa
--- /dev/null
+++ b/src/sh/misc.sh
@@ -0,0 +1,27 @@
+# err()
+# This is a helper function to print errors.
+#
+# @input $1: Error message
+err() {
+  echo "❌ $1" >/dev/tty
+}
+
+# Print date or datetime in a human and machine readable form.
+#
+# @input $1: Seconds since epoch
+__datetime_human_machine() {
+  s="$1"
+  t=$(date -d "@$s" +"%R")
+  dfmt="%F"
+  if [ "$t" != "00:00" ]; then
+    dfmt="$dfmt %R"
+  fi
+  date -d "@$s" +"$dfmt"
+}
+
+# Get summary string that can be used in for git-commit messages.
+#
+# @input $1: iCalendar file path
+__summary_for_commit() {
+  awk -v field="SUMMARY" "$AWK_GET" "$1" | tr -c -d "[:alnum:][:blank:]" | head -c 15
+}
diff --git a/src/sh/preview.sh b/src/sh/preview.sh
new file mode 100644
index 0000000..f4e1199
--- /dev/null
+++ b/src/sh/preview.sh
@@ -0,0 +1,51 @@
+# Preview helper functions
+# - month_previous
+# - month_next
+# - datetime_str
+
+# Print previous month of specified input month as <month> <year>.
+#
+# @input $1: Month
+# @input $2: Year
+month_previous() {
+  month=$(echo "$1" | sed 's/^0//')
+  year=$(echo "$2" | sed 's/^0//')
+  if [ "$month" -eq 1 ]; then
+    month=12
+    year=$((year - 1))
+  else
+    month=$((month - 1))
+  fi
+  echo "$month $year"
+}
+
+# Print next month of specified input month as <month> <year>.
+#
+# @input $1: Month
+# @input $2: Year
+month_next() {
+  month=$(echo "$1" | sed 's/^0//')
+  year=$(echo "$2" | sed 's/^0//')
+  if [ "$month" -eq 12 ]; then
+    month=1
+    year=$((year + 1))
+  else
+    month=$((month + 1))
+  fi
+  echo "$month $year"
+}
+
+# Print date or datetime in a human readable form.
+#
+# @input $1:              Seconds since epoch
+# @input $2.. (optoinal): Prepend date format
+datetime_str() {
+  s="$1"
+  shift
+  t=$(date -d "@$s" +"%R")
+  dfmt="$*%e %b %Y"
+  if [ "$t" != "00:00" ]; then
+    dfmt="$dfmt %R %Z"
+  fi
+  date -d "@$s" +"$dfmt"
+}
diff --git a/src/sh/theme.sh b/src/sh/theme.sh
new file mode 100644
index 0000000..25cd566
--- /dev/null
+++ b/src/sh/theme.sh
@@ -0,0 +1,8 @@
+GREEN="\033[1;32m"
+RED="\033[1;31m"
+WHITE="\033[1;97m"
+CYAN="\033[1;36m"
+STRIKE="\033[9m"
+ITALIC="\033[3m"
+FAINT="\033[2m"
+OFF="\033[m"
diff --git a/src/sh/view.sh b/src/sh/view.sh
new file mode 100644
index 0000000..fc19ae2
--- /dev/null
+++ b/src/sh/view.sh
@@ -0,0 +1,130 @@
+# View Functions
+# - __view_day
+# - __view_week
+# - __view_all
+
+# This function prints the view for the day specified in `$DISPLAY_DATE`.
+__view_day() {
+  weeknr=$(date -d "$DISPLAY_DATE" +"%G.%V")
+  files=$(grep "^$weeknr\ " "$WEEKLY_DATA_FILE" | cut -d " " -f 2-)
+  # Find relevant files in list of week files
+  sef=$({
+    set -- $files
+    for file in "$@"; do
+      file="$ROOT/$file"
+      awk \
+        -v collection_labels="$COLLECTION_LABELS" \
+        "$AWK_PARSE" "$file"
+    done
+  })
+  today=$(date -d "$DISPLAY_DATE" +"%D")
+  if [ -n "$sef" ]; then
+    sef=$(echo "$sef" | while IFS= read -r line; do
+      set -- $line
+      starttime="$1"
+      shift
+      endtime="$1"
+      shift
+      fpath="$(echo "$1" | sed 's/|/ /g')" # we will use | as delimiter (need to convert back!)
+      shift
+      collection="$1"
+      shift
+      status="$1"
+      shift
+      description="$(echo "$*" | sed 's/|/:/g')" # we will use | as delimiter
+      #
+      daystart=$(date -d "$today 00:00:00" +"%s")
+      dayend=$(date -d "$today 23:59:59" +"%s")
+      line=""
+      if [ "$starttime" -gt "$daystart" ] && [ "$starttime" -lt "$dayend" ]; then
+        s=$(date -d "@$starttime" +"%R")
+      elif [ "$starttime" -le "$daystart" ] && [ "$endtime" -gt "$daystart" ]; then
+        s="00:00"
+      else
+        continue
+      fi
+      if [ "$endtime" -gt "$daystart" ] && [ "$endtime" -lt "$dayend" ]; then
+        e=$(date -d "@$endtime" +"%R")
+      elif [ "$endtime" -ge "$dayend" ] && [ "$starttime" -lt "$dayend" ]; then
+        e="00:00"
+      else
+        continue
+      fi
+      echo "$s|$e|$starttime|$endtime|$fpath|$collection|$description|$status"
+    done)
+  fi
+  echo "$sef" | sort -n | awk -v today="$today" -v daystart="$DAY_START" -v dayend="$DAY_END" "$AWK_DAYVIEW"
+}
+
+# This function prints the view for the week that contains the day specified in `$DISPLAY_DATE`.
+__view_week() {
+  weeknr=$(date -d "$DISPLAY_DATE" +"%G.%V")
+  files=$(grep "^$weeknr\ " "$WEEKLY_DATA_FILE" | cut -d " " -f 2-)
+  dayofweek=$(date -d "$DISPLAY_DATE" +"%u")
+  delta=$((1 - dayofweek))
+  startofweek=$(date -d "$DISPLAY_DATE -$delta days" +"%D")
+  # loop over files
+  sef=$({
+    set -- $files
+    for file in "$@"; do
+      file="$ROOT/$file"
+      awk \
+        -v collection_labels="$COLLECTION_LABELS" \
+        "$AWK_PARSE" "$file"
+    done
+  })
+  if [ -n "$sef" ]; then
+    sef=$(echo "$sef" | while IFS= read -r line; do
+      set -- $line
+      starttime="$1"
+      shift
+      endtime="$1"
+      shift
+      #fpath="$1"
+      shift
+      collection="$1"
+      shift
+      status="$1"
+      shift
+      if [ "$status" = "TENTATIVE" ]; then
+        symb="$FAINT$CYAN"
+      elif [ "$status" = "CANCELLED" ]; then
+        symb="$STRIKE"
+      else
+        symb=""
+      fi
+      description="${symb:-}$*$OFF"
+      for i in $(seq 0 7); do
+        daystart=$(date -d "$startofweek +$i days 00:00:00" +"%s")
+        dayend=$(date -d "$startofweek +$i days 23:59:59" +"%s")
+        if [ "$starttime" -gt "$daystart" ] && [ "$starttime" -lt "$dayend" ]; then
+          s=$(date -d "@$starttime" +"%H:%M")
+          s="$s -"
+        elif [ "$starttime" -le "$daystart" ] && [ "$endtime" -gt "$daystart" ]; then
+          s="00:00 -"
+        else
+          continue
+        fi
+        if [ "$endtime" -gt "$daystart" ] && [ "$endtime" -lt "$dayend" ]; then
+          e=$(date -d "@$endtime" +"%H:%M")
+          e="- $e"
+        elif [ "$endtime" -ge "$dayend" ] && [ "$starttime" -lt "$dayend" ]; then
+          e="- 00:00"
+        else
+          continue
+        fi
+        echo "$i $s$e >$description"
+      done
+    done)
+  fi
+  sef=$({
+    echo "$sef"
+    seq 0 7
+  } | sort -n)
+  echo "$sef" | awk -v startofweek="$startofweek" "$AWK_WEEKVIEW"
+}
+
+# This function prints all entries.
+__view_all() {
+  cat "$APPROX_DATA_FILE"
+}