6 ms·

Ask HN: What's the best obscure but useful CLI tool?

26 points by lordleft 4y ago

john-tells-all 4y ago
entr -- when a file changes, run a command I use this on literally 100% of my projects. Normally it's "when my source changes, run tests" or sometimes "when files change, do 'terraform plan' to see what would change". Using this one command shortens developer feedback loops from a minute to microseconds! And you don't have to think about it! It's magic. `ls -1 *.py | entr pytest` `git ls-files | entr terraform plan` For more, see our friend and national treasure Julia Evans: https://jvns.ca/blog/2020/06/28/entr/ https://jvns.ca/blog/2020/06/28/entr/
- lordleft 4y ago
  That is incredible, I had no idea this existed -- thanks for sharing!
- qup 4y ago
  20+ years of linux, didn't know about it. Will be daily-driving it now, thanks for chiming in.
- rthomas6 4y ago
  That's awesome. Seems like it would pair well with Make.
  - coreyp_1 4y ago
    I use inotifywait with make for a similar effect. I save a source file and my code is re-compiled and tests are run. I love it!
    - deleted 4y ago
      [deleted]
  - john-tells-all 4y ago
    absolutely. 100% of my projects use Entr ("run thing on file change"), and Make ("use short name to run a complex script, e.g. test -> pytest").
anthonyhn 4y ago
GNU Parallel is pretty useful. You can use it to run command line programs in parallel. For example, if you wanted to gzip compress all individual files in a directory and limit the number of jobs equal to the number of CPU cores on your machine: ls | parallel --dry-run --jobs `nproc` 'gzip {}' (Note you have to remove the --dry-run switch to actually run this, --dry-run only prints out the commands parallel will run, not actually execute them)
- qhwudbebd 4y ago
  Sometimes xargs -P is useful too, but it's much more limited than GNU parallel.
  - hayst4ck 4y ago
    I think `xargs -P -I` is probably the closest thing to magic when it comes to commands.
rthomas6 4y ago
yes: literally just type y, or whatever string, over and over again. yes | annoying_interactive_install_script.sh
hosteur 4y ago
jdupes I find myself using it rather frequently. It is fantastic to find duplicate files.

26 points by lordleft 4y ago

entr -- when a file changes, run a command I use this on literally 100% of my projects. Normally it's "when my source changes, run tests" or sometimes "when files change, do 'terraform plan' to see what would change". Using this one command shortens developer feedback loops from a minute to microseconds! And you don't have to think about it! It's magic. `ls -1 *.py | entr pytest` `git ls-files | entr terraform plan` For more, see our friend and national treasure Julia Evans: https://jvns.ca/blog/2020/06/28/entr/ https://jvns.ca/blog/2020/06/28/entr/

lordleft 4y ago
That is incredible, I had no idea this existed -- thanks for sharing!
qup 4y ago
20+ years of linux, didn't know about it. Will be daily-driving it now, thanks for chiming in.
rthomas6 4y ago
That's awesome. Seems like it would pair well with Make.
- coreyp_1 4y ago
  I use inotifywait with make for a similar effect. I save a source file and my code is re-compiled and tests are run. I love it!
  - deleted 4y ago
    [deleted]
- john-tells-all 4y ago
  absolutely. 100% of my projects use Entr ("run thing on file change"), and Make ("use short name to run a complex script, e.g. test -> pytest").

anthonyhn 4y ago

GNU Parallel is pretty useful. You can use it to run command line programs in parallel. For example, if you wanted to gzip compress all individual files in a directory and limit the number of jobs equal to the number of CPU cores on your machine: ls | parallel --dry-run --jobs `nproc` 'gzip {}' (Note you have to remove the --dry-run switch to actually run this, --dry-run only prints out the commands parallel will run, not actually execute them)

qhwudbebd 4y ago
Sometimes xargs -P is useful too, but it's much more limited than GNU parallel.
- hayst4ck 4y ago
  I think `xargs -P -I` is probably the closest thing to magic when it comes to commands.

rthomas6 4y ago

yes: literally just type y, or whatever string, over and over again. yes | annoying_interactive_install_script.sh

hosteur 4y ago

jdupes I find myself using it rather frequently. It is fantastic to find duplicate files.