mail: Syncmail checks for existence of dependencies before use

In its default pre- and post-hooks, `neomutt-syncmail` now checks if
`imapfilter` and `notmuch` exist before invoking them.

Similarly, it defaults to `pass open` opening a pass coffin if
`pass-coffin` exists.

office/.local/bin/neomutt-syncmail

@@ -39,26 +39,35 @@
 # MBSYNC_PASSWORD_FILE="/path/to/gpg/file.gpg"
 
 # What to run before and after decrypting the password file.
-PASSWORD_CMD="pass open -t 1min"
+if pass coffin -v 1>/dev/null 2>&1; then
+    PASSWORD_CMD="pass open -t 1min"
+fi
+
 # POST_PASSWORD_CMD=""
 
+PING_TARGET="9.9.9.9"
+
 prehook() {
-    if [ -n "$MBSYNC_PRE" ]; then
+    if [ "$MBSYNC_PRE" != "" ]; then
         eval "$MBSYNC_PRE"
         return 0
     fi
     checkwarnuser
-    imapfilter -c "${XDG_CONFIG_HOME:-$HOME/.config}/imapfilter/config.lua"
+    if command -v imapfilter 1>/dev/null 2>&1; then
+        imapfilter -c "${XDG_CONFIG_HOME:-$HOME/.config}/imapfilter/config.lua"
+    fi
 }
 
 posthook() {
-    if [ -n "$MBSYNC_POST" ]; then
+    if [ "$MBSYNC_POST" != "" ]; then
         eval "$MBSYNC_POST"
         return 0
     fi
 
-    notmuch new 2>/dev/null
+    if command -v notmuch 1>/dev/null 2>&1; then
-    countnew
+        notmuch new 2>/dev/null
+        countnew
+    fi
 }
 
 # use notmuch to index incoming mail and set the
@@ -70,7 +79,7 @@ countnew() {
 
 # fail the routine and optionally send a message why
 fail() {
-    [ -n "$1" ] && echo "$1"
+    [ "$1" != "" ] && echo "$1"
     exit 1
 }
 
@@ -80,7 +89,7 @@ checkmail() {
 
 checkonline() {
     # Ping 1.1.1.1 to confirm that we are on the internet
-    ping -c 1 "1.1.1.1" >/dev/null 2>/dev/null || fail "checkmail can not access the internet."
+    ping -c 1 "$PING_TARGET" >/dev/null 2>/dev/null || fail "checkmail cannot access the internet."
 }
 
 # warn user that he has to enter his password in a moment
@@ -94,15 +103,15 @@ checkwarnuser() {
 }
 
 enablegpgagent() {
-    [ -n "$agt" ] && return
+    [ "$agt" != "" ] && return
 
-    if [ -n "$PASSWORD_CMD" ]; then
+    if [ "$PASSWORD_CMD" != "" ]; then
         IFS=" " read -r -a PASSWORD_CMD <<<"$PASSWORD_CMD"
         # shellcheck disable=SC2068
-        agt=$(${PASSWORD_CMD[@]})
+        agt=$("${PASSWORD_CMD[@]}")
     fi
 
-    if [ -n "$POST_PASSWORD_CMD" ]; then
+    if [ "$POST_PASSWORD_CMD" != "" ]; then
         IFS=" " read -r -a POST_PASSWORD_CMD <<<"$POST_PASSWORD_CMD"
         "${POST_PASSWORD_CMD[@]}"
     fi
@@ -138,7 +147,7 @@ if [ "$1" = "raw" ]; then
     checkmail
     exit
 # any other argument passed through selects mbsync targets
-elif [ -n "$1" ]; then
+elif [ "$1" != "" ]; then
     selected_mailbox="$1"
 fi
 
@@ -153,7 +162,7 @@ main() {
         fi
 
         tries=$((tries + 1))
-        if [ $tries -gt "${MBSYNC_MAX_TRIES:-3}" ]; then
+        if [ "$tries" -gt "${MBSYNC_MAX_TRIES:-3}" ]; then
             fail "maximum retries reached without success."
         fi
     done

office/.local/bin/notmuch-contacts

@@ -1,7 +1,7 @@
 #!/usr/bin/env sh
 # gets known e-mail adresses out of the current notmuch database
 #
-# called like `mail-searchcontacts [myadress]`
+# called like `notmuch-contacts [myadress]`
 #
 # where myaddress can be anything that connects mails to their adresses:
 # if directly found in the 'from': field, it will return those adresses