style(unitproc):appendArgTar(): cat instead of tee /dev/null

[BK-2020-03.git] / unitproc / bktemp-checkMakeTar

#!/bin/bash
# Desc: Checks that a valid tar archive exists, creates one otherwise

#===BEGIN Declare local script functions===
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
checkMakeTar() {
    # Desc: Checks that a valid tar archive exists, creates one otherwise
    # Usage: checkMakeTar [ path ]
    # Version: 1.0.2
    # Input: arg1: path of tar archive
    # Output: exit code 0 : tar readable
    #         exit code 1 : tar missing; created
    #         exit code 2 : tar not readable; moved; replaced
    # Depends: bash 5, date 8, tar 1, try()
    local pathTar returnFlag0 returnFlag1 returnFlag2
    pathTar="$1";

    # Check if file is a valid tar archive
    if tar --list --file="$pathTar" 1>/dev/null 2>&1; then
	## T1: return success
	returnFlag0="tar valid";
    else
	## F1: Check if file exists
	if [[ -f "$pathTar" ]]; then
	    ### T: Rename file
	    try mv "$pathTar" "$pathTar""--broken--""$(date +%Y%m%dT%H%M%S)" && \
		returnFlag1="tar moved";
	else
	    ### F: -
	    :
	fi;
	## F2: Create tar archive, return 0
	try tar --create --file="$pathTar" --files-from=/dev/null && \
	    returnFlag2="tar created";
    fi;
    
    # Determine function return code
    if [[ "$returnFlag0" = "tar valid" ]]; then
	return 0;
    elif [[ "$returnFlag2" = "tar created" ]] && ! [[ "$returnFlag1" = "tar moved" ]]; then
	return 1; # tar missing so created
    elif [[ "$returnFlag2" = "tar created" ]] && [[ "$returnFlag1" = "tar moved" ]]; then
	return 2; # tar not readable so moved; replaced
    fi;
} # checks if arg1 is tar; creates one otherwise
#===END Declare local script functions===

#====BEGIN sample code====
#myFile="/tmp/$(date +%s)..tar"
myFile="/tmp/$(date +%Y%m%d).tar"
if [[ -f "$myFile" ]]; then yell "$myFile already exists."; else yell "$myFile doesn't yet exist."; fi
if checkMakeTar "$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====

# Author: Steven Baltakatei Sandoval
# License: GPLv3+