fstail - scan a directory for changed files and tail them

What's this for?

When you need to see the output from all changed files within a directory.

Why doesn't tail -f /var/logs/* work?

Unfortunately, tail -f /logs/* may not do what you want it to do. Bash will expand * to all existing files within /logs/ and then show the extra lines added to each of them.

It also will not recurse down, any levels deeper than the current directory.

How is fstail different then?

fstail uses the gopkg.in/fsnotify to detect both new files, and existing files that are changed. It then starts concatenting their contents to the terminal.

I needed this for actuated.dev which launches microVMs on servers for CI.

Each VM launched will create a different file at: /var/log/actuated/GUID.txt, and tail -f * would only find existing files.

Usage

Tail the current directory:

cd /var/log/actuated
fstail


[7cd0d139b24d9cd30e3ad9ce7afcfe5999d2bf20.txt] [   12.770522] bash[1191]: 2023-03-22 11:04:00Z: Running job: arkade-e2e (run-job)
[49c8f4be774730ff6e5070166fc34ac25dc0e320.txt] [   13.363398] bash[1183]: 2023-03-22 11:04:00Z: Running job: arkade-e2e (k3sup)

To turn off the file prefix, set FS_PREFIX=0.

[   12.770522] bash[1191]: 2023-03-22 11:04:00Z: Running job: arkade-e2e (run-job)
[   13.363398] bash[1183]: 2023-03-22 11:04:00Z: Running job: arkade-e2e (k3sup)

Tail files in a given directory:

fstail /var/log/nginx/

By default, the base filename is going to be printed as a prefix for each tailed file:

1e51959055fb132720d03584388b5ac738689798.txt | Booting Linux Kernel.. OK
13d461e989733fa0f75df5227debab4be3504726.txt | Shutting down in 30s... 

To suppress the prefix, run the command with FS_PREFIX=0.

Installation

Download a release binary:

• fstail releases

Or download via arkade:

curl -SLs https://get.arkade.dev | sh

arkade get fstail

Or install via Go to install from source:

go install github.com/alexellis/fstail

If you need Go on a Linux system:

curl -sLS https://get.arkade.dev | sudo sh
sudo arkade system install go

If you wish to build multi-arch binaries on your own machine:

make dist

License

Copyright Alex Ellis 2023

MIT license.