Skip to content

Bash And Gnu Tricks

Tricks in GNU and bash

These are combined because you usually mash them together into a result.

History

Taken from https://www.washington.edu/computing/unix/history.html

It is also possible to use certain words from commands and do a regular expression type modifier. This may not be worth learning.

  • !! repeat last command
  • !-n repeat n commands ago, examples:
    • !-2, repeat 2 commands ago
    • !-1 == !!, repeat last command
  • !n repeat nth command as indexed in history command
  • !<substring> repeats most recent command beginning with <substring>

strace - trace system calls and signals

  1. Example: sudo strace -f -o slack.trace su robbintt -c 'slack'

I used this to trace where my ubuntu 16.04 slack app was silently failing. I thought it must be a file permissions error because the command slack would run for root but not for user. Strace showed me the files touched before failing.

Use ctrl+r and start typing. This 'reverse-I-search' is a more convenient way to search history.

It is also a nice trick to tag commands you will need.

For example:

ls -la /some/long/directory # mytag

Then just search the tag in reverse i search