task-logger.sh

Shell library to log tasks with nice output. Supports zsh and bash.

Property	Value
Version	1.3.4
Author	Eduardo San Martin Morote
License	The MIT License
Requirements	perl With Time::HiRes (comes by default in almost every Linux and in osx).

Example

#! /bin/bash

# Load the lib
source task-logger.sh

# Print some information message
info "Logs are available at $LOG_DIR"

# Print a message and do the corresponding message
# If the task fails, treat it as an error
working -n "Taking a nap"
log_cmd nap sleep 3 || ko

# Print a summary about what have been done
finish

Don't forget to call finish at the end (It is not mandatory, but summaries are cool)!

Motivation

When writing shell scripts you usually want to perform tasks with minimal output while logging everything somewhere else in order to check it later. Critical tasks should stop the script when they fail. At the end you should have a summary about errors, warnings and successes.

Everything with colors and unicode to make your shell look :sparkles:fabulous:sparkles:.

Features

• 🍭Colors
• Timers: every task displays the elapsed time
• Customizable:
  • Change any color
  • Create your own messages functions with 2 lines of code
  • Create your own progress loop (see Working loop)
• Critical tasks
• Summary
• Can be killed
• Smart cleanup

Usage

Initialisation

As every shell lib you start by sourcing it: source task-logger.sh

Messages

The lib has some printing functions defined. Every one of them follows this structure:

warning() {
  parse_opt "$@"
  echo ${opts[@]} "${WARNING_COLOR}${args[@]}${RESET_COLOR}"
}

You can define your own functions adding more text and changing colors. You can use printf or any other printing functions instead of echo. See Working loop for an example.

The available functions are:

• important: prints a message with a blue background so it is quite visible
• warning: prints a message in yellow
• good: prints a message in green
• bad: prints a message in red
• info: prints a message in gray
• error: prints a message in white with red background. best fit for critical errors
• ok, ko and warn increments the numbers of successes, errors and warnings, respectively. They also print fancy unicode characters
• working: prints the current time with format [HH:MM:SS] in info color and the prints a message in blue. This function is usually called with the -n option (no end line) and just before calling log_cmd.

Logs

Launch tasks with log_cmd:

# log_cmd [-c] <task-name> <command> || (ko|warn)

log_cmd -c critical-task sleep 2 || ko
log_cmd error-task not-a-cmd || ko
log_cmd warn-task not-a-cmd || warn

# prints a summary
finish

Cleanup

All of the logs are carefully saved in a temporary directory. This directory is created when task-logger.sh is sourced and stored at $LOG_DIR.

When you call the finish method the temporary directory is cleaned up if there were no errors. You can also pass the --force-cleanup option to clean the $LOG_DIR anyways. You can also manually cleanup by calling the tmp_cleanup.

If you need to create a new log dir use the new_log_dir method. This will populate the $LOG_DIR variable but will not clean up the previous directory. To do so you must either call the finish method (which will eventually clean if there are no errors) or the tmp_cleanup method.

Customization

A good example about how to customize the lib is in my blog where I use task-logger.sh to log my dotfiles install script while keeping a nice output.

Working loop

When I talk about working loop I refer to the loop called once a task is launched. In the first version of task-logger.sh I was using dot_working, which can still be used by setting the variable WORKING to dot_working and WORKING_END to true. By default the lib use turning_circle and turning_circle_end. Creating your own functions is easy:

• One have an infinite loop and should call itself (while true; do ...; done)
• The other one is called when the loop is stopped. It can be used to move the cursor backwards like I do in turning_circle_end using printf "\033[3D".

If you implement some cool working loop, please create a pull request so everyone can enjoy it 😄.

Here is an example of another working loop:

spinner() {
  local p n symbols
  p=1
  n=6
  symbols=()
  symbols[1]=" ◜ "
  symbols[2]=" ◠ "
  symbols[3]=" ◝ "
  symbols[4]=" ◞ "
  symbols[5]=" ◡ "
  symbols[6]=" ◟ "

  #trap 'printf "\033[5D "; return' SIGINT
  #trap 'printf "\033[3D "; return' SIGHUP SIGTERM

  printf "   "
  while true; do
    printf "\033[3D${symbols[$p]}"
    ((p++))
    if [[ "$p" > "$n" ]]; then
      p=1
    fi
    sleep 0.1
  done
}

spinner_end() {
  printf "\033[3D "
}

WORKING=spinner
WORKING_END=spinner_end

Releases

You can find release history in CHANGELOG.md.

When updating the lib a new version must be released in a separated commit. This commit must only contain the following additions:

• HISTORY.md: new release entry
• README.md: update version
• task-logger.sh: update version and date

TODO

• improve cygwin compatibility. It does work at the moment except for the missing unicode characters. Ctrl+C is printing as it should
• Use some kind of template for working loops and share some variables with it from the log_cmd method

Support on Beerpay

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