All commands (14,187)

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

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

Find corrupted jpeg image files
Finds all corrupted jpeg files in current directory and its subdirectories. Displays the error or warning found. The jpeginfo is part of the jpeginfo package in debian. Should you wish to only get corrupted filenames, use cut to extract them : $ find ./ -name *jpg -exec jpeginfo -c {} \; | grep -E "WARNING|ERROR" | cut -d " " -f 1

A Console-based Audio Visualizer for ALSA
# Installing apt search cava sudo apt install cava # modify the default config to change the colors by their hex color code cava -p mkdir ~/.cava nano ~/.cava/config cava # run with changes!

Count Files in a Directory with Wildcards.
Remove the '-maxdepth 1' option if you want to count in directories as well

Grep without having it show its own process in the results
The trick here is to use the brackets [ ] around any one of the characters of the grep string. This uses the fact that [?] is a character class of one letter and will be removed when parsed by the shell. This is useful when you want to parse the output of grep or use the return value in an if-statement without having its own process causing it to erroneously return TRUE.

Command to keep an SSH connection open
This runs the uptime command every 30 seconds to avoid an SSH connection dropping due to inactivity. Granted there are better ways of solving this problem but this is sometimes the right tool for the job.

Print text string vertically, one character per line.
Define a function $ vert () { echo $1 | grep -o '.'; } Use it to print some column headers $ paste

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

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

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"


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: