Commands by psykotron

Commands by psykotron (4)

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Find common groups between two users
This is sample output - yours may be different.
2

grep -xFf <(groups user1|cut -f3- -d\ |sed 's/ /\n/g') <(groups user2|cut -f3- -d\ |sed 's/ /\n/g')

psykotron · 2015-03-04 18:23:59 8
Figure out what shell you're running

short, sweet, and works after sudoing a new shell. Show Sample Output
This is sample output - yours may be different.
```
  PID TTY          TIME CMD
 9155 pts/0    00:00:00 bash
```
3

ps -p $$

psykotron · 2011-02-05 16:22:17 3
Extract tarball from internet without local saving
This is sample output - yours may be different.
8

curl http://example.com/a.gz | tar xz

psykotron · 2009-12-20 18:47:49 3
Another Matrix Style Implementation

A bit different from some of the other submissions. Has bold and uses all c printable characters. Change the bs=value to speed up and increase the sizes of the bold and non-bold strings.
This is sample output - yours may be different.
5

echo -ne "\e[32m" ; while true ; do echo -ne "\e[$(($RANDOM % 2 + 1))m" ; tr -c "[:print:]" " " < /dev/urandom | dd count=1 bs=50 2> /dev/null ; done

psykotron · 2009-12-19 19:05:04 4

What's this?

commandlinefu.com is the place to record those command-line gems that you return to again and again. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

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Remove old kernel packages

Find out when your billion-second anniversary is (was).

This is the same command as this one, but for OS X. http://www.commandlinefu.com/commands/view/3053/find-out-when-your-billion-second-anniversary-is-was.

Search some text from all files inside a directory

Get all files of particular type (say, PDF) listed on some wegpage (say, example.com)

See man wget if you want linked files and not only those hosted on the website.

Real full backup copy of /etc folder

Yes, rsync(1) supports local directories. And, should anything change, it's trivial to run the command again, and grab only the changes, instead of the full directory.

Press ctrl+r in a bash shell and type a few letters of a previous command

In the sample output, I pressed ctrl+r and typed the letters las. I can't imagine how much typing this has saved me.

Convert all files for iPhone with HandbrakeCLI

Find brute force attempts on SSHd

Searches the /var/log/secure log file for Failed and/or invalid user log in attempts.

Show IP Address in prompt --> PS1 var

when working with many machines in a computer lab need to know the IP addr is very large, this is a simplistic solution to make things easier

Determine if a command is in your $PATH using POSIX

it is generally advised to avoid using which(1) whenever possible. which(1) is usually a csh(1) script, or sometimes a compiled binary. It's output is highly variable from operating system to operating system, so platform independent scripts could become quite complicated with the logic. On HP-UX 10.20, for example, it prints "no bash in /path /path /path ..."; on OpenBSD 4.1, it prints "bash: Command not found."; on Debian (3.1 through 5.0 at least) and SuSE, it prints nothing at all; on Red Hat 5.2, it prints "which: no bash in (/path:/path:...)"; on Red Hat 6.2, it writes the same message, but on standard error instead of standard output; and on Gentoo, it writes something on stderr. And given all these differences, it's still variable based on your shell. This is why POSIX is king. See http://mywiki.wooledge.org/BashFAQ/081 for more ways on avoiding which(1).

Stay in the loop…

Follow the Tweets.

Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.

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Use your favourite RSS aggregator to stay in touch with the latest commands. There are feeds mirroring the 3 Twitter streams as well as for virtually every other subset (users, tags, functions,…):

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