What's this?

commandlinefu.com is the place to record those command-line gems that you return to again and again.

Delete that bloated snippets file you've been using and share your personal repository with the world. 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.

If you have a new feature suggestion or find a bug, please get in touch via http://commandlinefu.uservoice.com/

Get involved!

You can sign-in using OpenID credentials, or register a traditional username and password.

First-time OpenID users will be automatically assigned a username which can be changed after signing in.


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:



2011-03-12 - Confoo 2011 presentation
Slides are available from the commandlinefu presentation at Confoo 2011: http://presentations.codeinthehole.com/confoo2011/
2011-01-04 - Moderation now required for new commands
To try and put and end to the spamming, new commands require moderation before they will appear on the site.
2010-12-27 - Apologies for not banning the trolls sooner
Have been away from the interwebs over Christmas. Will be more vigilant henceforth.
2010-09-24 - OAuth and pagination problems fixed
Apologies for the delay in getting Twitter's OAuth supported. Annoying pagination gremlin also fixed.




Commands tagged alsa from sorted by
Terminal - Commands tagged alsa - 13 results
amixer -c 0 set Master 1dB+
2013-07-25 15:28:45
User: chrisp6825
Functions: amixer set

adjusts the 'Master' channel's volume up by 1dB.

Can use command 'amixer' to see other channels :

Simple mixer control 'Master',0


Simple mixer control 'Capture',0

f=220;echo "int s=16e3/$f;main(i){unsigned char v[s];read(0,v,s);for(;;)putchar(v[i%s]=(v[i%s]+v[++i%s])/2);}"|gcc -x c -&&./a.out</dev/urandom|aplay -d 2
2013-06-28 14:52:53
User: tehdog
Functions: aplay echo gcc
Tags: alsa sh gcc

outputs a f=220Hz guitar string sound (fifth string A)

needs ALSA

amixer -c 0 set Master 100%
2013-03-28 16:30:10
User: thewarden
Functions: amixer set

Replace "Master" with desired control name (e.g. Front, Earphone, PCM, etc.).

a=$(xwininfo |gawk 'BEGIN {FS="[x+ \t]*"} /-geometry/ {print int(($3+1)/2)*2"x"int(($4+1)/2)*2"+"$5"+"$6}') ; echo ${a} ; ffmpeg -f x11grab -s ${a} -r 10 -i :0.0 -sameq -f mp4 -s wvga -y /tmp/out.mpg
2012-08-31 14:48:41
User: dwygo
Functions: echo gawk

Now we can capture only a specific window (we have to chose by clicking on it)

ffmpeg complains about "Frame size must be a multiple of 2" so we calculate the upper even number with (g)awk trickery.

We remove the grep, we are already using (g)awk here ....why losing time with grep !!! ;)

aumix -v +5
2011-07-24 07:41:40
User: h3xx
Functions: aumix
Tags: alsa


aumix -v -5

Map these to key combinations in your window manager and who needs special buttons?

sox -t alsa default ./recording.flac silence 1 0.1 5% 1 1.0 5%
2011-03-08 14:36:39
User: sairon

Records audio from your mic in FLAC (Free Lossless Audio Codec) format, starts only after it detects at least 0.1 seconds of noise and stops after 1 second of silence. You can adjust the percent values (sensitivity) to best fit your microphone and voice (0.1% if you have a great quality mic, higher if you don't, 0% does not trim anything).

Useful for speech recognition in conjunction with my previous command titled 'Google voice recognition "API"' (http://www.commandlinefu.com/commands/view/8043/google-voice-recognition-api).

ssh [user]@[host] "ogg123 -" < [podcast].ogg
ssh [user]@[address] "mpg321 -" < [file].mp3
2010-07-30 00:23:13
User: leovailati
Functions: ssh

This one doesn't need to convert to wav.

sox Klaxon.mp3 -t wav - |ssh thelab@company.com paplay
2010-07-29 23:23:39
User: camocrazed
Functions: ssh

This will allow you to convert an audio file to wav format, and send it via ssh to a player on the other computer, which will open and play it there. Of course, substitute your information for the sound file and remote address

You do not have to use paplay on the remote end, as it is a PulseAudio thing. If the remote end uses ALSA, you should use aplay instead. If it uses OSS, you should berate them about having a lousy sound system. Also, you're not limited to transmitting encoded as wav either, it's just that AFAIK, most systems don't come with mp3 codecs, but will play wav files fine.

If you know SoX is installed on the remote end and has mp3 codecs, you can use the following instead:

cat Klaxon.mp3 |ssh thelab@company.com play -t mp3 -

this will transmit as mp3. Again, use your specific information. if you're not playing mp3s, use another type with the -t option

lsof /dev/snd/pcm*p /dev/dsp | awk ' { print $2 }' | xargs kill
2010-07-23 20:24:16
User: alustenberg
Functions: awk xargs

for when a program is hogging the sound output. finds, and kills. add -9 to the end for wedged processes. add in 'grep ^program' after lsof to filter.

ffmpeg -f alsa -itsoffset 00:00:02.000 -ac 2 -i hw:0,0 -f x11grab -s $(xwininfo -root | grep 'geometry' | awk '{print $2;}') -r 10 -i :0.0 -sameq -f mp4 -s wvga -y intro.mp4
2010-03-31 09:33:05
User: mohan43u
Functions: awk grep

Yet another x11grab using ffmpeg. I also added mic input to the capturing video stream using alsa. Yet I need to find out how to capture audio which is currently playing.

ffmpeg -f alsa -ac 2 -i hw:1,0 -acodec libmp3lame -ab 96k output.mp3
2009-09-16 12:45:44
User: ivalladt

Record audio to an MP3 file via ALSA. Adjust -i argument according to arecord -l output.

ffmpeg -f alsa -r 16000 -i hw:2,0 -f video4linux2 -s 800x600 -i /dev/video0 -r 30 -f avi -vcodec mpeg4 -vtag xvid -sameq -acodec libmp3lame -ab 96k output.avi
2009-09-15 17:03:25
User: ivalladt

Record from a webcam, audio using ALSA encoded as MP3, video as MPEG-4.