logtail_crystal

An implementation of the logtail command written in Crystal Lang

Behavior:

• Checks the byte size of a file and compares it to the offset. If the byte size has increased it prints out any new lines.
• If the inode has changed it starts from the beginning
• If the file size is smaller than the offset, it starts from the beginning

To build on Ubuntu 22:

• Make sure you have Crystal 1.8.2 installed
• Clone the repo: git clone https://github.com/weirdbricks/logtail_crystal.git
• Build: crystal build --static --release --no-debug logtail.cr
• Strip: strip logtail
• Run: ./logtail

Optionally also move to /usr/local/bin

crystal build --static --release --no-debug logtail.cr
strip logtail
mv ./logtail /usr/local/bin/

Usage instructions:

This command requires 1 argument which is the logfile you want to view. Subsequent runs of the command against the same logfile will only display any new lines.

Optionally you can provide a second argument which is the offset file that you want to use. If you do not provide an offset filename, one will be created for you under /tmp/#{filename}.offset.

Example 1 - Getting new lines from /var/log/syslog

./logtail /var/log/syslog

Example 2 - Getting new lines from /var/log/syslog and creating an offset filename at /dev/shm/buhahaha

./logtail /var/log/syslog /dev/shm/buhahaha

Example 3 - Getting new lines from /var/log/syslog without diagnostics:

./logtail /var/log/syslog /dev/shm/buhahaha 2>/dev/null