Follow does not seem to follow continuous log files

[jlanzarotta]

Hello,

I am trying to have hl follow a ever growing log file. However, then I run hl --follow test.log, hl shows me a few lines and then nothing happens. No further updates are show, even thought the file is continuously being written to. I would have expected it to continuously follow the end of the log file as it grows. Am I missing something? Thanks.

[pamburus]

Hello, could you please share the details?

• What is your operating system type, distribution and version?
• Which hl version do you use?
• Does tail -F work well for this file?

[jlanzarotta]

I am not 100% sure the fix is working. If I open the desired log file with hl -F logfile.log, the contents of the file are shown, but as more information is being written to the file, the new content is not shown. HOWEVER, if I open another PowerShell terminal and run tail -f logfile.log WHILE hl -F logfile.log is also running in the other PowerShell terminal, hl seems to work correctly and tails the file continuously...

[pamburus]

Could you let me know if the file is on a local disk or a network share?

If it is on a local disk, could you also run hl with HL_DEBUG_LOG=trace environment variable while it does not behave properly and share the debug log messages?

[jlanzarotta]

It is on local disk.

Here is the log...

[2026-06-11T18:08:37.735410Z DEBUG hl] logging initialized
[2026-06-11T18:08:37.742784Z DEBUG hl::settings] added configuration file optional search path: C:\ProgramData\hl\config
[2026-06-11T18:08:37.743048Z DEBUG hl::settings] added configuration file optional search path: C:\Users\JLanzarotta\AppData\Roaming\hl\config
[2026-06-11T18:08:37.743243Z DEBUG hl::settings] added configuration file required search path: C:\Users\jlanzarotta\.config\hl\config.toml
[2026-06-11T18:08:37.748129Z DEBUG hl::themecfg::theme] loading theme: uni
[2026-06-11T18:08:37.748331Z TRACE hl::themecfg::theme] searching for theme 'uni' in custom directory: C:\Users\JLanzarotta\AppData\Roaming\hl\themes
[2026-06-11T18:08:37.748773Z TRACE hl::themecfg::theme] theme 'uni' not found in custom directory, trying embedded themes
[2026-06-11T18:08:37.749010Z TRACE hl::themecfg::theme] found embedded theme file: uni.toml
[2026-06-11T18:08:37.749431Z DEBUG hl::themecfg::theme] loaded theme 'uni' from embedded resources
[2026-06-11T18:08:37.749658Z DEBUG hl::themecfg::theme] merging theme 'uni' with @base
[2026-06-11T18:08:37.749876Z TRACE hl::themecfg::theme] found embedded theme file: @base.toml
[2026-06-11T18:08:37.750415Z DEBUG hl::themecfg::raw] merging theme 'uni' (v1.1) into '@base' (v1.1)
[2026-06-11T18:08:37.750653Z TRACE hl::themecfg::raw] theme 'uni' is not tagged as overlay, updating metadata
[2026-06-11T18:08:37.750862Z TRACE hl::themecfg::raw] merge complete: '@base' <- 'uni'
[2026-06-11T18:08:37.751069Z DEBUG hl::themecfg::theme] loading overlay theme: @accent-italic
[2026-06-11T18:08:37.751247Z TRACE hl::themecfg::theme] searching for theme '@accent-italic' in custom directory: C:\Users\JLanzarotta\AppData\Roaming\hl\themes
[2026-06-11T18:08:37.751617Z TRACE hl::themecfg::theme] theme '@accent-italic' not found in custom directory, trying embedded themes
[2026-06-11T18:08:37.751800Z TRACE hl::themecfg::theme] found embedded theme file: @accent-italic.toml
[2026-06-11T18:08:37.751990Z DEBUG hl::themecfg::theme] loaded theme '@accent-italic' from embedded resources
[2026-06-11T18:08:37.752161Z DEBUG hl::themecfg::theme] merging overlay '@accent-italic' into theme chain
[2026-06-11T18:08:37.752328Z DEBUG hl::themecfg::raw] merging theme '@accent-italic' (v1.1) into 'uni' (v1.1)
[2026-06-11T18:08:37.752500Z TRACE hl::themecfg::raw] theme '@accent-italic' is tagged as overlay, preserving base metadata
[2026-06-11T18:08:37.752671Z TRACE hl::themecfg::raw] merge complete: 'uni' <- '@accent-italic'
[2026-06-11T18:08:37.752849Z TRACE hl::themecfg::theme] resolving final theme
[2026-06-11T18:08:37.753556Z DEBUG hl] configured input info layouts: auto
[2026-06-11T18:08:37.754201Z DEBUG hl] * resolved input info layouts: none | minimal | compact | full
[2026-06-11T18:08:37.754659Z DEBUG hl] * terminal is wide enough to show full input info
[2026-06-11T18:08:37.755386Z DEBUG hl] holding 1 inputs
[2026-06-11T18:08:37.756304Z DEBUG hl::pager::selection] selecting pager for Follow mode
[2026-06-11T18:08:37.756622Z DEBUG hl::pager::selection] env var HL_PAGER not set or empty, skipping candidate
[2026-06-11T18:08:37.756874Z DEBUG hl::pager::selection] simple env candidate PAGER skipped: not supported in follow mode
[2026-06-11T18:08:37.774230Z DEBUG hl::pager::selection] profile "less" does not support follow mode, disabling pager
[2026-06-11T18:08:37.774523Z DEBUG hl::pager::selection] no pager selected, using stdout
[2026-06-11T18:08:37.775035Z DEBUG hl] run the app
[2026-06-11T18:08:37.779686Z DEBUG hl::input] detecting format of random access stream
[2026-06-11T18:08:37.780526Z DEBUG hl::input] format detected: Some(Verbatim)

[pamburus]

Does this debug log include the rotation of the observed log files?
I do not see here any messages from the filesystem monitoring crate, this is strange.

[jlanzarotta]

I see the log lines I provided above and 10 lines of the actual log file. That is it. The log is definitely being written to because I see the output using other log file viewers like lnav or BaretailPro in real time...

[jlanzarotta]

Another interesting this is that while doing hl -F logfile.log in one PowerShell terminal, if I open another PowerShell terminal, do a cd to the directory where the log file is located. And, then simply issue a lsd command in that directory, hl updates... The lsd program must be doing something to file to make hl pick up any changes... FYI, lsd is from https://github.com/lsd-rs/lsd.

[pamburus]

Yes, I know lsd, I am using it as well.

What program is writing to logfile.log?
If you do not run any commands to make hl update the state, does the problem appear only when logfile.log is rotated or it appears even when the file is appended?

[pamburus]

I can confirm that I was able to reproduce the issue. I will investigate it further.

[pamburus]

I noticed that when I run lsd -la --size bytes I see how the file grows on each call.
But if I run ls it does not change.
It looks like lsd somehow forces lumberjack to flush the file, until that it seems to buffer the data somewhere.

[pamburus]

Please try the latest version from master branch.

[jlanzarotta]

Fantastic! Your latest updates seem to have worked!

[pamburus]

Great to hear that. I will release a new version soon.

[pamburus]

Fixed in v0.36.3.