What does || mean in .screenrc?

Command based on Rampion's command

screen /bin/sh -c '/usr/bin/man `cat "[email protected]"` > /tmp/manual | less /tmp/manual || read'

|| read does not mean or in the command. read seems to be a built-in -command about which I did not find explanation in my OS X's manuals.

What does || mean in the command?

-------------Problems Reply------------

|| is nearly 'or' operator.

In the code example above it will first run less /tmp/manual and if it returns a value that is not true it will run read. If the first command returns a true value then the read command is not performed because of short circuiting.

Thanks to Michiel: please note that the operator is not commutative such that it is not mathematical OR.

What MitMaro said. It's a parameter for the shell, or /bin/sh in this case. (Technically it's not a "parameter" (that's a different term) but it's part of the shell's "grammar.")

For details, you can read the man page on sh. What you're looking for is under the "Lists" section.


An OR list has the form

command1 || command2

command2 is executed if and only if command1 returns a non-zero exit status.

The return status of AND and OR lists is the exit status of the last command executed in the list.

Category:screen Views:0 Time:2009-07-12
Tags: screen

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