Commands by polar

Commands by polar (5)

sorted by

Generate trigonometric/log data easily

If you want a sequence that can be plotted, do: seq 8 | awk '{print "e(" $0 ")" }' | bc -l | awk '{print NR " " $0}' Other bc functions include s (sine), c (cosine), l (log) and j (bessel). See the man page for details. Show Sample Output
This is sample output - yours may be different.
```
2.71828182845904523536
7.38905609893065022723
20.08553692318766774092
54.59815003314423907811
148.41315910257660342111
403.42879349273512260838
1096.63315842845859926372
2980.95798704172827474359
```
0

seq 8 | awk '{print "e(" $0 ")" }' | bc -l

polar · 2010-08-14 02:52:39 4
I finally found out how to use notify-send with at or cron

The simplest way to do it. Works for me, at least. (Why are the variables being set?)
This is sample output - yours may be different.
4

echo notify-send test | at now+1minute

polar · 2010-08-08 03:11:11 7
Base conversions with bc

Easily convert numbers to their representations in different bases. Passing "ibase=16; obase=8; F2A" to bc will convert F2A (3882 in decimal) from Hex to Octal, and so on. Show Sample Output
This is sample output - yours may be different.
```
$ echo "obase=2; 27" | bc -l
11011
$ echo "ibase=16; F2A" | bc -l
3882
$ echo "ibase=16; obase=8; F2A" | bc -l
7452
```
20

echo "obase=2; 27" | bc -l

polar · 2009-03-25 09:54:50 39
Quick calculator at the terminal

Useful for quick calculations at the command line. $math_expr is any arithmetic expression (see sample output): 4.5*16+3^2 s(3.1415926/2) More options in the bc man page. Show Sample Output
This is sample output - yours may be different.
```
$ echo "4.5*16+3^2" | bc -l
81.0
$ echo "s(3.1415926/2)" | bc -l
.99999999999999964101
```
2

echo "$math_expr" | bc -l

polar · 2009-03-25 09:46:01 5
Easy Regex based mass renaming

Allows for quick mass renaming, assuming the user has some familiarity with regular expressions. Basically, it replaces the original_file_name in the output of ls with "mv -v original_file_name new_file_name" and passes the output to sh. Show Sample Output
This is sample output - yours may be different.
```
$ ls ~/manga/ | sed -rn -e 's/naruto_(...\.zip)/mv -v & \1/p' | sh
`naruto_431.zip' -> `431.zip'
`naruto_432.zip' -> `432.zip'
`naruto_433.zip' -> `433.zip'
`naruto_434.zip' -> `434.zip'
$
```
-2

ls /some/directory | sed -rn -e 's/input_file_regex/mv -v & output_file_name/p' | sh

polar · 2009-03-25 09:20:15 10

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.

Share Your Commands

Check These Out

Clone perms and owner group from one file to another

Copy both perms and owner group from one file to another.

rename all images in folder with prefix of date and time from exif data

imagemagick is required

Mysql uptime

show Mysql uptime

"Pretty print" $PATH, show directories in $PATH, one per line with replacement pattern using shell parameter expansion

Can be used to create path alias. From: https://www.cyberciti.biz/tips/bash-aliases-mac-centos-linux-unix.html. #9

Show drive names next to their full serial number (and disk info)

As of this writing, this requires a fairly recent version of util-linux, but is much simpler than the previous alternatives. Basically, lsblk gives a nice, human readable interface to all the blkid stuff. (Of course, I wouldn't recommend this if you're going to be parsing the output.) This command takes all the fun out of the previous nifty pipelines, but I felt I ought to at least mention it as an alternative since it is the most practical.

Extract audio from Mythtv recording to Rockbox iPod using ffmpeg

There are some pretty good live performances on late night TV. With Mythtv I record David Letterman, Jimmy Fallon, and Conan nightly all in HD from over the air broadcasts. If I find a live performance I like I copy it to my Rockboxed iPod using this command. The Rockbox firmware knows how to downmix 5.1 audio. The command above extracts the audio from the video starting at 58 minutes and 15 seconds. It ends at the end of the file since this was the last performance of the recording. The command creates an ac3 file. I copy the ac3 file to my Rockbox iPod and rock on.

Filter out all blank or commented (starting with #) lines

Get all IPs via ifconfig

works on Linux and Solaris. I think it will work on nearly all *nix-es

find external links in all html files in a directory list

Just a handy way to get all the unique links from inside all the html files inside a directory. Can be handy on scripts etc.

Show apps that use internet connection at the moment.

show only the name of the apps that are using internet

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.

» http://twitter.com/commandlinefu
» http://twitter.com/commandlinefu3
» http://twitter.com/commandlinefu10

Subscribe to the feeds.

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,…):

Subscribe to the feed for:

» all commands
» commands with 3 up-votes (commandlinefu3)
» commands with 10 up-votes (commandlinefu10)
» commands by polar