commandlinefu.com is the place to record those command-line gems that you return to again and again.
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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.
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,…):
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host is a simple utility for performing DNS lookups. It is normally used to convert names to IP addresses and vice versa. When no arguments or options are given, host prints a short summary of its command line arguments and options.
bc is a wonderful calculator. Just type bc at the command line and have at it. Ctrl+D (or type quit) will get you out. This usage is just scratching the surface: bc can handle a mini scripting language, complete with variable, statements, loop, conditional statements and more. Do a man page on it to find out.
Short and sweet command. This command is also useful for other information such as what IP address a particular user logged in from, how long had they been logged in, what shell do they use.
tested in csh on solaris.
Sometimes you want to know the summary of the sizes of directories without seeing the details in their subdirectories. Especially if it is going to just scroll off the screen. This one liner summarizes the disk usage of any number of directories in a directory without giving all the details of whats happening underneath.
Run this in your music folder, or give the path directly after "find".
The sed pattern filters away the basename.
That will capture 200 seconds of video at fullscreen 1680x1050 resolution, but scaled down 25 percent, with 15 frames per second.
Be aware of using the --password argument as it will appear your password in plain text on the screen. You may use -p argument instead, it will prompt you to enter you password in hidden mode.
grep -- displays process ids
-v -- negates the matching, displays all but what is specified in the other options
-u -- specifies the user to display, or in this case negate
The process loops through all PIDs that are found by pgrep, then orders a forced kill to the processes in numerical order, effectively killing the parent processes first including the shells in use which will force the users to logout.
Tested on Slackware Linux 12.2 and Slackware-current
Handy if all you have is a console session or tty.
Depending on the network setup, you may not get the hostname.
Display which user run process from given port name
The --parents option will cause cp or mkdir to automatically create the parent directory structure.
mkdir --parents /one/two/three/dir
will create /one, /one/two, and /one/two/three as needed before creating dir. cp will copy files with their full directory structure into the target directory with this option.
Thanks to Peter Leung at:
which has good examples of usage.