Log & Debug BASH shell Scripts

log-cleanup.sh

A generic directory cleanup script that removes files older than the retension period.

Retension Period is specified on the command line using -r N where N is Days

Directory to cleanup is specified using -d /path/to/log/directory

The script wil lalso remove empty directories afer the retension period has exipred.

CRONTAB usage

Sample entries shown below are taken from a CRON file:

45 4 * * * /usr/local/bin/log-cleanup.sh -r 90 -d /data/archive > /dev/null 2>&1

1 0 * * * /usr/local/bin/log-cleanup.sh -r 7 -d /data/beacon-data > /dev/null 2>&1

56 23 * * * /usr/local/bin/log-cleanup.sh -r 60 -d /logs > /dev/null 2>&1

log-functions.sh

This shell script can be sourced from your script and provides convienient logging operations for logging shell script output to a daily log file. By defualt it logs all files output to /logs/your-directory-here/

File Name Format

The log file name format is: /logs/your_dir/your_file-YYYY-MM-DD.log

File Format

The log file format is as follows:

====== Log Start =========
Time: Wed Feb 19 10:28:46 AEST 2025

2025-02-19|10:28:46|406803|OK|Variables
2025-02-19|10:28:46|406803|OK|           TMP_FILE = /tmp/wp-ha-hosts.txt
2025-02-19|10:28:46|406803|OK|           LOCKFILE = /tmp/check-ha-capacity.lock
2025-02-19|10:28:46|406803|OK|             Script = /usr/local/bin/check-cluster-capacity.sh
2025-02-19|10:28:46|406803|OK|
2025-02-19|10:28:46|406803|OK|Check for Lock File.
2025-02-19|10:28:46|406803|OK|Set trap on exit.
2025-02-19|10:28:46|406803|OK|Extract servers
...
2025-02-19|10:28:46|406803|OK|M1=0.0  M5=0.0  M15=0.0
2025-02-19|10:28:46|406803|OK|NoLoad() - Do Nothing
2025-02-19|10:28:46|406803|OK|Not all servers are loaded

Time: Wed Feb 19 10:28:46 AEST 2025
====== Log End   =========

If you exclude the LogStart and LogEnd functions then you have a pure pipe formatted file that can be processed with other tools to extract and report on issues logged in the file.

Pipe format is:

YYYY-MM-DD|HH:MM:SS|PID|STATUS_CODE|Text Message - see LogMSG function

When used with the log-cleanup.sh shell script you have a uniform, convienient and self cleaning platform to log script activity each day.

Functions

function LogInit
function SetDirectory
function SetFilename
function SetLog
function LogStart
function LogEnd
function LogMsg
function LogError
function LogCritical

Usage

Add the following near the start of your script: source /usr/local/bin/log-functions.sh

Specify a directory

Specify a file name

Example (extract) :

#!/bin/bash
source /usr/local/bin/log-functions.sh

SetDirectory "cluster-capacity"
SetFilename  "check-every-minute"
LogInit
LogStart
LogMsg "Variables"
LogMsg "           TMP_FILE = ${TMP_FILE}"
LogMsg "           LOCKFILE = ${LOCKFILE}"
LogMsg "             Script = $0"
LogMsg " "
LogMsg "Check for Lock File."
set -C; 2>/dev/null > ${LOCKFILE}
if [ $? -eq 1 ]
then
   LogMsg "Lock [ ${LOCKFILE} ] exists - EXIT NOW."
   exit
fi
LogMsg "Set trap on exit."
trap "rm -f ${LOCKFILE} " EXIT

... rest of code

LogEnd

This creates a directory called /logs/cluster-capacity and a date stamped file