unitproc/bktemp-checkMakeTar

   1 #!/bin/bash
   2
   3 # Desc: Checks that a valid tar archive exists, creates one otherwise
   4
   5
   6 yell() { echo "$0: $*" >&2; }      #o Yell, Die, Try Three-Fingered Claw technique
   7 die() { yell "$*"; exit 111; }     #o Ref/Attrib: https://stackoverflow.com/a/25515370
   8 try() { "$@" || die "cannot $*"; } #o
   9
  10 #===BEGIN Declare local script functions===
  11 checkMakeTar() {
  12     # Desc: Checks that a valid tar archive exists, creates one otherwise
  13     # Usage: checkMakeTar [ path ]
  14     # Input: arg1: path of tar archive
  15     # Output: exit code 0 (even if tar had to be created)
  16     # Depends: try, tar, date
  17     local PATH_TAR="$1"
  18
  19     # Check if file is a valid tar archive
  20     if tar --list --file="$PATH_TAR" 1>/dev/null 2>&1; then
  21         ## T1: return success
  22         return 0;
  23     else
  24         ## F1: Check if file exists
  25         if [[ -f "$PATH_TAR" ]]; then
  26             ### T: Rename file
  27             try mv "$PATH_TAR" "$PATH_TAR""--broken--""$(date +%Y%m%dT%H%M%S)";
  28         else
  29             ### F: -
  30             :
  31         fi
  32         ## F2: Create tar archive, return 0
  33         try tar --create --file="$PATH_TAR" --files-from=/dev/null;
  34         return 0;
  35     fi
  36 } # checks if arg1 is tar; creates one otherwise
  37 #===END Declare local script functions===
  38
  39 #====BEGIN sample code====
  40 myFile="/tmp/$(date +%s)..tar"
  41 yell "$myFile doesn't yet exist."
  42 if checkMakeTar "$myFile"; then
  43     yell "checkMakeTar() function run and exited:$?";
  44 else
  45     yell "checkMakeTar() function run and exited:$?";
  46 fi
  47
  48 if [[ -f "$myFile" ]]; then
  49     yell "Now exists    :$myFile";
  50     ls -l "$myFile";
  51 else
  52     yell "Does not exist:$myFile";
  53     ls -l "$myFile";
  54 fi
  55 #====END sample code====