Bash Logger

logging module for bash scripts

This script is used to log messages to the console and to a log file and is designed to be similar the API of the python logging module. It includes log rotation by size and by number of log files.

There are a couple of additional functions to show how you could create custom logging functions for yourself.

There is a test script that you can run to see how the logging works.

Log rotation

Log rotation is handled by the rotateLogs function. When logging to a file is enabled, the rotateLogs function is called during each run and by default maintains a history of 5 runs. The number of log history files to maintain can be changed by calling the log_rotation_count function. The function creates a new copy of the log file with the next number in the sequence and then deletes the oldest log file. For example, if the log file is named "mylog.log" and the log_rotation_count is set to 5, the log files will be named "mylog.log.1", "mylog.log.2", "mylog.log.3", "mylog.log.4", and "mylog.log.5". When the rotation is full the log file will be renamed to "mylog.log.1" and the oldest log file, " mylog.log.5", will be deleted. The numbers are in reverse order so that the newest log file is always named "mylog.log".

log_rotation_count 10

Usage:

Import this file with the following statement near the top of your script

. ./logger.sh

By default, the level is set to INFO, colored logging to the screen is enabled, and logging to a file is disabled.

You can initialize the logging level, turn off/on logging to screen, and set the log file name ( which will turn logging to file on/off ) with the following function:

set_logging [log_level] [log_to_screen] [log_file_name]

Set the logging level to one of CRITICAL ERROR WARNING INFO DEBUG

set_log_level DEBUG

By default, the logs will rotate when the size is greater than 100 kb. You can change the size of the log file before it rotates with the following function:
NOTE: This function must be called before set_logging or log_file_name

log_file_rotate_size 10000 # 10 kb

Turn logging to screen on/off

log_to_screen true/false

Turn colors on/off (default is on) when logging to screen

log_color_output true/false

Set the log file name and turn on logging to that file. If you do not set the log file name, logging to file will be turned off. Once you set the log file name, logging to file will be turned on and log rotation will be enabled.

log_file_name /path/to/log/file

You can log to the screen and/or to a file with the following functions:

log_critical "This is a critical error"
log_error "This is an error"
log_warning "This is a warning"
log_info "This is a info log"
log_debug "This is a debug statement"

You can also run a command and log the output to the screen and/or to a file if you have set the log file name:
The output will be prepended and appended with a begin and end message.
This will run ls -l and log the output to the screen and/or to a file if you have set the log file name:

log_execute DEBUG ls -l

You can also create custom functions (which will log to the screen and/or to a file if you have set the log file name):
I have included a sample of two functions which you can use as examples of how to create your own custom functions.
First create a file to test with:

date &> /tmp/date.out

Then run the following commands: this will run cat /tmp/date.out and log the output to the screen and/or to a file if you have set the log file name:
The output will bre prepended and appended with a begin and end message.

log_cat_file /tmp/date.out

This will run ls -l /tmp/date.out and log the output to the screen and/or to a file if you have set the log file name:
The output will bre prepended and appended with a begin and end message.

log_info_file /tmp/date.out

Example:

The following is an example of how to use this script:
Import the script - by default, the level is set to INFO, colored logging to the screen is enabled, and logging to a file is disabled. Run an example of each standard log function Note that the debug line produces no output because the default log level is INFO log the execution lf ls -l create a sample file to test with which has hte date inside of it log the output of cat /tmp/date.out This will produce no output because the function is set to DEBUG and the default log level is INFO log the output of ls -l /tmp/date.out set the log level to DEBUG run a debug level log function to see that it now produces output

. ./logger.sh
log_critical "This is a critical error"
log_error "This is an error"
log_warning "This is a warning"
log_info "This is a info log"
log_debug "This is a debug statement"
log_execute INFO ls -l
date &> /tmp/date.out
log_cat_file /tmp/date.out
log_info_file /tmp/date.out
log_level DEBUG
log_debug "This is another debug statement"

License

See LICENSE file

Author

Written by: Leon Letto

Contributions

Contributions and suggestions are welcome. Please submit a pull request.

disaac / bashLogger