feat(unitproc):Add setTimeZoneEV function

Validates and sets timezone according to first argument. Otherwise
returns non-zero exit code.

diff --git a/unitproc/bktemp-setTimeZoneEV b/unitproc/bktemp-setTimeZoneEV
new file mode 100644 (file)
index 0000000..6933752
--- /dev/null
+++ b/unitproc/bktemp-setTimeZoneEV
@@ -0,0 +1,74 @@
+#!/bin/bash
+
+# Desc: Set time zone environment variable TZ
+
+yell() { echo "$0: $*" >&2; } # Yell, Die, Try Three-Fingered Claw technique; # Ref/Attrib: https://stackoverflow.com/a/25515370
+die() { yell "$*"; exit 111; }
+try() { "$@" || die "cannot $*"; }
+setTimeZoneEV(){
+    # Desc: Set time zone environment variable TZ
+    # Usage: setTimeZoneEV arg1
+    # Input: arg1: 'date'-compatible timezone string (ex: "America/New_York")
+    #        TZDIR env var (optional; default: "/usr/share/zoneinfo")
+    # Output: exports TZ
+    #         exit code 0 on success
+    #         exit code 1 on incorrect number of arguments
+    #         exit code 2 if unable to validate arg1
+    # Depends: yell, die, try
+    ARG1="$1"
+    local tzDir returnState
+    if ! [[ $# -eq 1 ]]; then
+       yell "ERROR:Invalid argument count.";
+       return 1;
+    fi
+
+    # Read TZDIR env var if available
+    if printenv TZDIR 1>/dev/null 2>&1; then
+       tzDir="$(printenv TZDIR)";
+    else
+       tzDir="/usr/share/zoneinfo";
+    fi
+    
+    # Validate TZ string
+    if ! [[ -f "$tzDir"/"$ARG1" ]]; then
+       yell "ERROR:Invalid time zone argument.";
+       return 2;
+    else
+    # Export ARG1 as TZ environment variable
+       TZ="$ARG1" && export TZ && returnState="true";
+    fi
+
+    # Determine function return code
+    if [ "$returnState" = "true" ]; then
+       return 0;
+    fi
+} # Exports TZ environment variable
+
+#==BEGIN sample code==
+date --iso-8601=seconds; echo "==============="; sleep 2
+
+date --iso-8601=seconds
+cmd1="setTimeZoneEV America/New_York"
+echo "Running:$cmd1"; $cmd1; echo "Exit code:$?"
+date --iso-8601=seconds; echo "==============="; sleep 2
+
+date --iso-8601=seconds
+cmd2="setTimeZoneEV Asia/Tokyo"
+echo "Running:$cmd2"; $cmd2; echo "Exit code:$?"
+date --iso-8601=seconds; echo "==============="; sleep 2
+
+date --iso-8601=seconds
+cmd3="setTimeZoneEV";
+echo "Running:$cmd3"; $cmd3; echo "Exit code:$?"
+date --iso-8601=seconds; echo "==============="; sleep 2
+
+date --iso-8601=seconds
+cmd4="setTimeZoneEV Pacific/Lemuria"
+echo "Running:$cmd4"; $cmd4; echo "Exit code:$?"
+date --iso-8601=seconds; echo "==============="; sleep 2
+#==END sample code==
+
+# Author: Steven Baltakatei Sandoval
+# License: GPLv3+
+
+