agelimit

Quickly test a file against an age limit in your shell scripts

Examples

Check if a file is over 12 hours old:

agelimit -v 12h ./downloaded_file.json

agelimit: Error, limit breached! ./downloaded_file.json is over 12h old.

Age limit errors use exit code 1.

Check if a file is over 1 day old:

agelimit -v 1d ./ETL.log

agelimit: Success! ./ETL.log is less than 1 day old

Age limit successes use exit code 0.

Program Usage

Usage: ./agelimit [OPTIONS] maxage file

  maxage      The maximum age for your file and a unit specifier. For example, 100s
              for 100 seconds, 20m for 20 minutes, 3h for 3 hours or 2d for 2 days
  file        The path to the file to be tested
  -s    Silence all output
  -v    Enable verbose output
  -version
        Display the version number and quit

Real World Usage

So, how would you use this in a script?

Say you had a data pipeline that needs to be run infrequently, but the data can't be more than 4 hours old for business reasons. You could add something like the following to your script:

(In all of the following examples we're checking an age limit of 4 hours for the file, etl.log)

#!/usr/bin/env bash

if ./agelimit 4h ./etl.log; then 
    echo "File not old yet"
    # Proceed as normal
else
    echo "File is now old"
    # regenerate the file
fi

Or in a simpler form:

#!/usr/bin/env bash

if ! ./agelimit 4h ./etl.log; then 
    echo "File is now old"
    # regenerate the file
fi

An example that uses the explicit exit code emitted by agelimit:

#!/usr/bin/env bash

if ./agelimit 4h ./etl.log; then 

if [[ $? -eq 0 ]]; then 
    echo "File not old yet"
    # Proceed as normal
else
    echo "File is now old"
    # regenerate the file
fi

Exit codes

The standard exit codes used by agelimit are as follows:

Age limit not breached - 0
Age limit breached - 1
Program error - 99

This last one includes things like input typos and specifying files that don't exist and so on. Always check your agelimit commands run as expected before you push them to production! Test with the -v flag to see verbose output.

Tips and tricks

Use in a Makefile or justfile to regenerate files if they're older than business rules dictate
Use in build scripts to make sure you don't hammer resources
Use in data pipelines to only regenerate files when necessary
Use with log files for ETL, to ensure the ETL itself is as fresh as required.

Building agelimit

This project uses a Makefile to build the various target architectures. You'll also need Go installed. Run make to build them all. All builds end up in a "builds" directory.

License

This project is released under the MIT License. See LICENSE.md file for more info.

sellorm / agelimit