Created
February 17, 2016 15:41
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| #!/bin/bash | |
| # === global variables ================================================ | |
| LOCKBASE="/var/lock" # old | |
| #LOCKBASE="/run/lock" # new | |
| # === support functions =============================================== | |
| # --- display usage information --------------------------------------- | |
| action_usage() { | |
| BN=$(basename $0) | |
| cat <<EOF | |
| usage: ${BN} [ no-lock-test | lock-test | help ] | |
| EOF | |
| } | |
| # --- display extended usage information ------------------------------ | |
| action_help() { | |
| cat <<EOF | |
| To be done... | |
| EOF | |
| } | |
| # --- a simple test --------------------------------------------------- | |
| action_no_lock_test() { | |
| SECS="$1" | |
| if [ -z "${SECS}" ] | |
| then | |
| SECS="3" | |
| fi | |
| echo -n "TEST: about to sleep ${SECS}s..." | |
| sleep "${SECS}" | |
| echo " done." | |
| } | |
| # --- locking test ---------------------------------------------------- | |
| action_lock_test() { | |
| LOCKFILE="$1" | |
| CALLFUNC="$2" | |
| shift | |
| shift | |
| if [ -z "${LOCKFILE}" ] | |
| then | |
| echo "Error: no lockfile name specified!" >&2 | |
| exit 1 | |
| fi | |
| if [ -z "${CALLFUNC}" ] | |
| then | |
| echo "Error: no function to call specified!" >&2 | |
| exit 1 | |
| fi | |
| # - - locking section - begin - - - - - - - - - - - - - - - - - - - - - | |
| ( | |
| flock -x -n 234 | |
| if [ "$?" = "0" ] | |
| then | |
| # call the important function within the locked context | |
| "${CALLFUNC}" $* | |
| # clear lockfile, because we must have created it | |
| rm "${LOCKFILE}" | |
| # don't do any important stuff here | |
| exit 0 | |
| else | |
| echo "Error: Failed to acquire lock!" >&2 | |
| exit 1 | |
| fi | |
| ) 234>"${LOCKFILE}" | |
| # - - locking section - end - - - - - - - - - - - - - - - - - - - - - - | |
| } | |
| # === main entry point ================================================ | |
| case $1 in | |
| nt|no-lock-test) | |
| shift | |
| action_no_lock_test $1 | |
| ;; | |
| lt|lock-test) | |
| shift | |
| action_lock_test "${LOCKBASE}/script-lock-test.lck" "action_no_lock_test" "$1" | |
| ;; | |
| help) | |
| action_usage | |
| action_help | |
| ;; | |
| *) | |
| action_usage | |
| exit 1 | |
| ;; | |
| esac | |
| exit 0 | |
| # --- end of file --- |
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