In less is there a command for reloading a file from disk, so that less will show any changes made to a file since less was started? This would saving me have to terminate and restart less if I want to see changes to the file I'm viewing.
3 Answers
There are two possibly relevant commands detailed in the fine manual for less(1)
R Repaint the screen, discarding any buffered input. Useful if the file is changing while it is being viewed. F Scroll forward, and keep trying to read when the end of file is reached. Normally this command would be used when already at the end of the file. It is a way to monitor the tail of a file which is growing while it is being viewed. (The behavior is similar to the "tail -f" command.)R for repaint does not always reload the file.[1]
A workaround that always reloads the file is to press hq, which will open the Help page, then quit. It has a side effect of forcing the file to reload.
[1] Here are some examples of situations that R do and do not reload:
>and>>changes: DO get reloadedsed -i, gEdit, TextEdit: DO NOT get reloaded- On Linux,
vichanges: DO get reloaded - On Mac,
vichanges: DO NOT get reloaded
I believe the difference comes down to whether the inode changes (you can check with ls -i foo.txt). If the inode changes, then R will not work.
I worked around this problem using a shell script that auto-reloads less on exit:
while true; do less -K file.txt || exit; doneWith this script, I can hit q to reload the file, and CTRL+C to exit back to the bash shell. The CTRL+C behavior is enabled via the -K option. Your last search term will be preserved.
This can be further refactored by using the colon (:) to create an empty expression, via do : ...
while less -K file.txt; do : ; doneDrawbacks
The current viewing position will always be rest to line 0.
Practical Example using mintty
In my windows (GitBash) environment I set up a script that opens a new terminal window (mintty) for less-viewing a file:
lesswin() { mintty bash -c "while less -K \"$@\"; do : ; done;" & }
