http://veejoe.net/blog Vic's Blog Sat, 31 Dec 2011 13:29:24 +0000 en hourly 1 http://wordpress.org/?v=3.3 http://veejoe.net/blog/2008/12/the-difference-between-pipe-and-redirection/ http://veejoe.net/blog/2008/12/the-difference-between-pipe-and-redirection/#comments Thu, 04 Dec 2008 00:58:29 +0000 Vic http://veejoe.net/blog/?p=101 Newcomers to UNIX-like operating systems are often confused by the difference between the shell operations pipe and redirection. The difference is easily explained with an example, in the context of web development. The shell command echo "st=1" | ./lifeswork.pl shows how a pipe is used to supply command line input to a script usually invoked via CGI in a web server. This allows the script to be more easily debugged by testing at the command line. The shell command echo "st=1" > ./lifeswork.pl shows how redirection uses command line input to overwrite a script file, destroying the file and the web developer's sanity. Hopefully this example illustrates the difference between pipe and redirect, and helps you avoid the idiotic mistake I just made.

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