Ask HN: What are your top most useful Unix commands?

chmielewski | karma 87 | avg karma 0.43 · 2019-10-31 16:26:15+00:00

time cat

apotatopot | karma 87 | avg karma 0.58 · 2019-10-31 16:27:13

top

jk, but also not.

w !sudo tee % in vim, even tho that's not really directly a unix thing?

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hntddt1 | karma 6 | avg karma 0.25 · 2019-10-31 16:30:54

0x445442 | karma 2020 | avg karma 1.74 · 2019-10-31 16:35:52+00:00

dirs -v pushd popd

wbsun | karma 456 | avg karma 1.67 · 2019-10-31 16:41:07

cd pwd ls

jjjbokma | karma 149 | avg karma 0.74 · 2019-10-31 17:57:55+00:00

find, grep

antoineMoPa | karma 1858 | avg karma 3.0 · 2019-10-31 18:21:43+00:00

grep, find, tail -f (useful to look at log files as they update)

Extras: sort, uniq, sed, sftp, apropos, man

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jjjbokma | karma 149 | avg karma 0.74 · 2019-10-31 21:00:34

tail -F

This will also follow a log file if it rotates.

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jolmg | karma 5592 | avg karma 2.09 · 2019-10-31 23:10:18

I just found out a few days ago that `-F` works with multiple files, too. When there's new content on one, tail prefixes the output with a header, telling you what file it is.

I've used that to watch all logs apache and descendant processes could be writing to:

  pstree -p $(pgrep -o apache2) \
  | grep -Po '[^}]\(\K\d+'
  | sed ':b;N;$!bb;s/\n/,/g' \
  | sudo xargs lsof -d 0-1000 -a -p \
  | grep -Po '\S+$' \
  | grep 'log' \
  | sort -u \
  | xargs tail -F

potta_coffee | karma 1730 | avg karma 1.54 · 2019-10-31 19:12:01+00:00

history | grep <command halfway remember using>

sgillen | karma 1696 | avg karma 2.59 · 2019-10-31 21:21:58+00:00

emacs&

kleer001 | karma 2611 | avg karma 1.01 · 2019-10-31 21:52:11

the semicolon ";" for chaining commands

ls -l

the "alias" command in a file for setting up quick-commands

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runjake | karma 12875 | avg karma 3.04 · 2019-10-31 22:59:06+00:00

cut, awk, sed, comm, grep

jolmg | karma 5592 | avg karma 2.09 · 2019-10-31 23:02:31

simonblack | karma 2316 | avg karma 0.51 · 2019-11-01 01:20:32+00:00

ls, find, grep, tar, cpio

But in truth, it's the bash scripting 'glue' that holds everything together.

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DrScump | karma 6029 | avg karma 1.06 · 2019-11-01 08:23:48+00:00

kill lets you send any signal to a process you have control over. Corresponding signal handlers allow a wide range of behavior changes.

ksaj | karma 2486 | avg karma 0.81 · 2019-11-01 22:48:34

A lot of people only know about its use for literally killing a process. But as an example of where I find myself using it fairly often is:

kill -USR1 <dd>

where <dd> is the process ID (obtained from ps) for the dd command.

Instead of killing dd, it reports back how much has been read/copied so far. Especially useful for working with large files and you decide you want to guestimate how much longer the copy will take.

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