Skip to content

Instantly share code, notes, and snippets.

@goodmami
Last active March 30, 2023 03:49
  • Star 31 You must be signed in to star a gist
  • Fork 4 You must be signed in to fork a gist
Star You must be signed in to star a gist
Embed
What would you like to do?
Basic logging commands for Linux shell scripts
#!/bin/bash
##
## Simple logging mechanism for Bash
##
## Author: Michael Wayne Goodman <goodman.m.w@gmail.com>
## Thanks: Jul for the idea to add a datestring. See:
## http://www.goodmami.org/2011/07/simple-logging-in-bash-scripts/#comment-5854
## Thanks: @gffhcks for noting that inf() and debug() should be swapped,
## and that critical() used $2 instead of $1
##
## License: Public domain; do as you wish
##
exec 3>&2 # logging stream (file descriptor 3) defaults to STDERR
verbosity=3 # default to show warnings
silent_lvl=0
crt_lvl=1
err_lvl=2
wrn_lvl=3
inf_lvl=4
dbg_lvl=5
notify() { log $silent_lvl "NOTE: $1"; } # Always prints
critical() { log $crt_lvl "CRITICAL: $1"; }
error() { log $err_lvl "ERROR: $1"; }
warn() { log $wrn_lvl "WARNING: $1"; }
inf() { log $inf_lvl "INFO: $1"; } # "info" is already a command
debug() { log $dbg_lvl "DEBUG: $1"; }
log() {
if [ $verbosity -ge $1 ]; then
datestring=`date +'%Y-%m-%d %H:%M:%S'`
# Expand escaped characters, wrap at 70 chars, indent wrapped lines
echo -e "$datestring $2" | fold -w70 -s | sed '2~1s/^/ /' >&3
fi
}
@gffhcks
Copy link

gffhcks commented Sep 21, 2015

Shouldn't "debug" be at a higher level of verbosity than "info"?

Also, why does $2 get used instead of $1 for critical()?

@goodmami
Copy link
Author

@gffhcks, sorry to be so late to respond. I didn't get any notification for your comment.

And thanks for pointing these out. Debug and Info are in the unconventional order because I didn't closely check with what other logging frameworks do. I'm not sure why I used $2 in critical(); that's just a bug. I'll fix both of these.

@MapleLove2014
Copy link

Hello, what does this statement means: sed '2~1s/^/ /' ?

@goodmami
Copy link
Author

@MapleLove2014, that indents the wrapped lines. 2~1 means to perform the following operation on every line starting from the 2nd (every 1 line after line 2), then s/^/ / is a substitution operation that matches the beginning of each line (^) and inserts two spaces. In a terminal you might try man sed to get more info about the command.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment