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defragment files
Thanks to flatcap for optimizing this command. This command takes advantage of the ext4 filesystem's resistance to fragmentation. By using this command, files that were previously fragmented will be copied / deleted / pasted essentially giving the filesystem another chance at saving the file contiguously. ( unlike FAT / NTFS, the *nix filesystem always try to save a file without fragmenting it ) My command only effects the home directory and only those files with your R/W (read / write ) permissions. There are two issues with this command: 1. it really won't help, it works, but linux doesn't suffer much (if any ) fragmentation and even fragmented files have fast I/O 2. it doesn't discriminate between fragmented and non-fragmented files, so a large ~/ directory with no fragments will take almost as long as an equally sized fragmented ~/ directory The benefits i managed to work into the command: 1. it only defragments files under 16mb, because a large file with fragments isn't as noticeable as a small file that's fragmented, and copy/ delete/ paste of large files would take too long 2. it gives a nice countdown in the terminal so you know how far how much progress is being made and just like other defragmenters you can stop at any time ( use ctrl+c ) 3. fast! i can defrag my ~/ directory in 11 seconds thanks to the ramdrive powering the command's temporary storage bottom line: 1. its only an experiment, safe ( i've used it several times for testing ), but probably not very effective ( unless you somehow have a fragmentation problem on linux ). might be a placebo for recent windows converts looking for a defrag utility on linux and won't accept no for an answer 2. it's my first commandlinefu command

Change SSH RSA passphrase
Protects your secret identity with a passphrase. OSX 10.6 automatically does key forwarding and can store the passphrase in the keychain. For other OSes, use ssh -A or set ForwardAgent in ssh_config to enable forwarding. Then use ssh-agent/ssh-add.

nohup that doesn't generate nohup.out
I'm sure this can be piped into another way. Please share!

Colored diff ( via vim ) on 2 remotes files on your local computer.
You can use $ vim scp://root@example.com//file too in a simple case.

Purge configuration files of removed packages on debian based systems
Purge all configuration files of removed packages

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Url Encode
It only encodes non-Basic-ASCII chars, as they are the only ones not well readed by UTF-8 and ISO-8859-1 (latin-1). It converts all * C3 X (some latin symbols like ASCII-extended ones) and * C2 X (some punctuation symbols like inverted exclamation) ...UTF-8 double byte symbols to escaped form that every parser understands to form the URLs. I didn't encode spaces and the rest of basic punctuation, but supposedly, space and others are coded as \x20, for example, in UTF-8, latin-1 and Windows-cp1252.... so its read perfectly. Please feel free to correct, the application to which I designe that function works as expected with my assumption. Note: I specify a w=999, I didn't find a flag to put unlimited value. I just suppose very improbable surpass the de-facto 255 (* 3 byte max) = 765 bytes length of URL

Interactively build regular expressions
txt2regex can be interactive or noninteractive and generates regular expressions for a variety of dialects based on user input. In interactive mode, the regex string builds as you select menu options. The sample output here is from noninteractive mode, try running it standalone and see for yourself. It's written in bash and is available as the 'txt2regex' package at least under debian/ubuntu.

Convert CSV to JSON
Replace 'csv_file.csv' with your filename.

All what exists in dir B and not in dir A will be copied from dir B to new or existing dir C
Assumed dir A, B, C are subdirs of the current dir Exact syntax of the command is: rsync -v -r --size-only --compare-dest=/path_to_A/A/ /path_to_B/B/ /path_to_C/C/ (do not omit end-slashes, since that would copy only the names and not the contents of subdirs of dir B to dir C) You can replace --size-only with --checksum for more thorough file differences validation Useful switch: -n, --dry-run perform a trial run with no changes made


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