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Command line tricks for smart geeks

Nov 17, 2009, 13:33 (3 Talkback[s])

"Make your own Bash wormholes

"Even for the Bash aficionado, the mkfifo command is likely to be one of the lesser used in your collection. It creates a pipe for sharing data, connecting two running utilities with a kind of command line wormhole. Data sent into one end will instantaneously appear at the other.

"Before we look at how to use it, it's worth going over how we typically see pipes. If you've used the shell for anything other than scaring your friends with cat /dev/random, you'll be used to the idea of pipes. They're most often used to stream the output of one program into the input of another. A common use is when there is too much textual output from one command to read. Piping this output into another - usually either less or more - lets you pause and page through the output in your own time:

cat /var/log/messages | less

"In this instance, the pipe is temporarily created for the execution of a single command, but using mkfifo it's possible to create persistent pipes that you can use for similar tasks."

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