CS155: Introduction to Unix

Spring 2018

Pipe

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Pipe vs. Semicolon

CS155 Pipe

Don’t do this

Students occasionally ask me why this doesn’t work:

% mkdir foo | cd foo
.script: line 10: cd: foo: No such file or directory

because they think that the pipe symbol (|) means “and then”.

It doesn’t!

What does the pipe do?

The pipe symbol means:

% echo -e 'my\ndog\nspot'
my
dog
spot
% echo -e 'my\ndog\nspot' | sort
dog
my
spot

Do this, instead

If you want to execute one command after another, just do so:

% mkdir foo
% cd foo

or:

% mkdir foo; cd foo

Note that using semicolon (;) is no less typing than just pressing the Enter key.

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Modified: 2017-12-26T16:52

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