Over a million developers have joined DZone.

A Simple Cron Wrapper Script With Logging

DZone's Guide to

A Simple Cron Wrapper Script With Logging

· DevOps Zone ·
Free Resource

Easily enforce open source policies in real time and reduce MTTRs from six weeks to six seconds with the Sonatype Nexus Platform. See for yourself - Free Vulnerability Scanner. 

When working with crontab service, one thing I often need is to capture the output of the job. Having the job script aware of this output and logging is tedious, and often make the script harder to read. So I wrote a shell wrapper that will redirect all job script's STDOUT into a log file. This way I can inspect it when a job has run and the job script can just focus on the task itself. 

# file: runcmd.sh
# Helper/wrapper script to run any command in the crontab env. This script will ensure
# user profile script is loaded and to log any command output into log files. It also
# ensure not to print anything to STDOUT to avoid crontab system mail alert.
# NOTE: be sure to pass in absolute path of the command to be run so it can be found.
# Usage:
#  ./runcmd.sh find $HOME/crontab/test.sh  # Simple use case
#  LOG_NAME=mytest ./runcmd.sh $HOME/crontab/test.sh # Change the log name to something specific

# Options
DIR=`dirname $0`
CMD_NAME=`basename $1`
LOG="$DIR/logs/$LOG_NAME.log`date +%s`"

# Ensure logs dir exists
if [[ ! -e $DIR/logs ]]; then
  mkdir -p $DIR/logs

# Run cron command
source $HOME/.bash_profile
echo "`date` Started cron cmd=$CMD, logname=$LOG_NAME" >> $LOG 2>&1
$CMD >> $LOG 2>&1
echo "`date` Cron cmd is done." >> $LOG 2>&1

With this wrapper, you can run any shell script and their output will be recorded. For example this job script below will clean up the logs accumulated in our logs folder.

Note that the wrapper will also auto source the ".bash_profile". Often this this is needed if your job script expect all the env variables you already have setup in your login shell scripts.

# file: remove-crontab-logs.sh 
DIR=`dirname $0`/logs
echo "Checking and removing logs in $DIR"
find $DIR -type f -mtime +31 -print -delete
echo "Done"

Now in the crontab file, you may run the job script like this:

# Clean up crontab logs
@montly $HOME/crontab/runcmd.sh $HOME/crontab/remove-crontab-logs.sh

Automate open source governance at scale across the entire software supply chain with the Nexus Platform. Learn more.


Published at DZone with permission of

Opinions expressed by DZone contributors are their own.

{{ parent.title || parent.header.title}}

{{ parent.tldr }}

{{ parent.urlSource.name }}