+#!/bin/bash
+
+# Desc: Checks that a valid tar archive exists, creates one otherwise
+
+
+yell() { echo "$0: $*" >&2; } #o Yell, Die, Try Three-Fingered Claw technique
+die() { yell "$*"; exit 111; } #o Ref/Attrib: https://stackoverflow.com/a/25515370
+try() { "$@" || die "cannot $*"; } #o
+
+#===BEGIN Declare local script functions===
+checkMakeTar() {
+ # Desc: Checks that a valid tar archive exists, creates one otherwise
+ # Usage: checkMakeTar [ path ]
+ # Input: arg1: path of tar archive
+ # Output: exit code 0 (even if tar had to be created)
+ # Depends: try, tar, date
+ local PATH_TAR="$1"
+
+ # Check if file is a valid tar archive
+ if tar --list --file="$PATH_TAR" 1>/dev/null 2>&1; then
+ ## T1: return success
+ return 0;
+ else
+ ## F1: Check if file exists
+ if [[ -f "$PATH_TAR" ]]; then
+ ### T: Rename file
+ try mv "$PATH_TAR" "$PATH_TAR""--broken--""$(date +%Y%m%dT%H%M%S)";
+ else
+ ### F: -
+ :
+ fi
+ ## F2: Create tar archive, return 0
+ try tar --create --file="$PATH_TAR" --files-from=/dev/null;
+ return 0;
+ fi
+} # checks if arg1 is tar; creates one otherwise
+#===END Declare local script functions===
+
+#====BEGIN sample code====
+myFile="/tmp/$(date +%s)..tar"
+yell "$myFile doesn't yet exist."
+if checkMakeTar "$myFile"; then
+ yell "checkMakeTar() function run and exited:$?";
+else
+ yell "checkMakeTar() function run and exited:$?";
+fi
+
+if [[ -f "$myFile" ]]; then
+ yell "Now exists :$myFile";
+ ls -l "$myFile";
+else
+ yell "Does not exist:$myFile";
+ ls -l "$myFile";
+fi
+#====END sample code====