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/
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.
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
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:
When aliens invade Earth, be first to warn your neighbours by placing your computer screen at a window and executing this potentially Earth-saving command.
Ctrl C when aliens are defeated.
to include hidden dirs use:
tree -adL 1
(with ls, requires 'ls -ad */ .*/')
Remounts a usb disk /dev/sdb, without having to physically remove and reinsert. (Gnome desktop)
for one line per process:
ss -p | cat
for established sockets only:
ss -p | grep STA
for just process names:
ss -p | cut -f2 -sd\"
or
ss -p | grep STA | cut -f2 -d\"
Get sopcast links for live sports from http://myp2p.eu (for example)
Get sp-sc or sp-auth binary by googling (sopcast + linux)
eg http://www.jbg.f2s.com/sp-sc.gz
Requires the 32bit libstdc++5 package.
After exiting mplayer, type 'killall sp-sc'
in place of warptv use shagadelictv, edgetv, agingtv, dicetv, vertigotv, revtv or quarktv (see 'gst-inspect-0.10 effectv'. Requires gstreamer-plugins-good (or gstreamer0.10-plugins-good ).
For slow webcams use something like
gst-launch-0.10 v4l2src ! video/x-raw-yuv,width=320,height=240 ! ffmpegcolorspace ! warptv ! ffmpegcolorspace ! autovideosink
.
For basic webcam view via gstreamer use
gst-launch-0.10 v4l2src ! autovideosink
emulates bash4's "echo {03..20}"
Uses bash3 builtin function printf
Flips the y-axis to emulate a real mirror, uses low resolution for speed, this will also hide blemishes and the like :)
Quick command to test your webcam. Press 'f' to toggle fullscreen. Can also use 'vlc v4l2://' if you want gui controls. For higher/smoother framerate lower the default resolution:
cvlc v4l2:// :v4l2-width=320 :v4l2-height=240 &
Launch a gui app remotely. In this example smplayer is installed on the remote machine, and movie.avi is in the remote user's home dir. Note that stdout/stderr is still local, so you'll have feedback locally, add '&>/dev/null' to suppress. This is surprisingly not well known (compared to running an X app locally via ssh -X). (NB. if your distro requires ~/.Xauthority file present, then try -fX if you have problems)
Resubmitted (and trimmed, thanks sitaram) due to ridiculous voting on previous submission. Fingers crossed, it gets a better rating this time.
The end of unix time and the 32bit era will be Tue Jan 19 03:14:07 UTC 2038
.
date -ud @$[2**31]
date: invalid date `@2147483648'
.
In 64bit you have much longer, at least to:
date -ud @$[2**55]
Sun Jun 13 06:26:08 UTC 1141709097
EDIT: Trolling crap removed ;)
takes approx 6 secs on a Core 2 Duo @ 2GHz, and 15 secs on atom based netbooks!
uses monoid (a,b).(x,y)=(ax+bx+ay,ax+by) with identity (0,1), and recursion relations:
F(2n-1)=Fn*Fn+F(n-1)*F(n-1)
F(2n)=(Fn+2*F(n-1))*Fn
then apply fast exponentiation to (1,0)^n = (Fn,F(n-1))
.
Note that: (1,0)^-1=(1,-1) so (a,b).(1,0) = (a+b,a) and (a,b)/(1,0)=(a,b).(1,0)^-1=(b,a-b)
So we can also use a NAF representation to do the exponentiation,http://en.wikipedia.org/wiki/Non-adjacent_form , it's also very fast (about the same, depends on n):
time echo 'n=1000000;m=(n+1)/2;a=0;b=1;i=0;while(m>0){z=0;if(m%2)z=2-(m%4);m=(m-z)/2;e[i++]=z};while(i--){c=a*a;a=c+2*a*b;b=c+b*b;if(e[i]>0){t=a;a+=b;b=t};if(e[i]<0){t=a;a=b;b=t-b}};if(n%2)a*a+b*b;if(!n%2)a*(a+2*b)' | bc
Calculates nth Fibonacci number for all n>=0, (much faster than matrix power algorithm from http://everything2.com/title/Compute+Fibonacci+numbers+FAST%2521 )
n=70332 is the biggest value at http://bigprimes.net/archive/fibonacci/ (corresponds to n=70331 there), this calculates it in less than a second, even on a netbook.
UPDATE: Now even faster! Uses recurrence relation for F(2n), see http://en.wikipedia.org/wiki/Fibonacci_number#Matrix_form
n is now adjusted to match Fn at wikipedia, so bigprimes.net table is offset by 1.
UPDATE2: Probably fastest possible now ;), uses a simple monoid operation:
uses monoid (a,b).(x,y)=(ax+bx+ay,ax+by) with identity (0,1), and recursion relations:
F(2n-1)=Fn*Fn+F(n-1)*F(n-1)
F(2n)=Fn*(2*F(n-1)+Fn)
then apply fast exponentiation to (1,0)^n = (Fn,F(n-1))
.
Note that: (1,0)^-1=(1,-1) so (a,b).(1,0) = (a+b,a) and (a,b)/(1,0)=(a,b).(1,0)^-1=(b,a-b)
So we can also use a NAF representation to do the exponentiation,http://en.wikipedia.org/wiki/Non-adjacent_form , it's also very fast (about the same, depends on n):
time echo 'n=70332;m=(n+1)/2;a=0;b=1;i=0;while(m>0){z=0;if(m%2)z=2-(m%4);m=(m-z)/2;e[i++]=z};while(i--){c=a*a;a=c+2*a*b;b=c+b*b;if(e[i]>0){t=a;a+=b;b=t};if(e[i]<0){t=a;a=b;b=t-b}};if(n%2)a*a+b*b;if(!n%2)a*(a+2*b)' | bc