05 August 2015

It is frequently seen in shell scripts that both stdout and stderr are redirected or piped to the same destination. Do you know that BASH (and some others) has shortcuts for that? Below is cited from BASH manual.

If |& is used, the standard error of COMMAND1 is connected to COMMAND2's standard input through the pipe; it is shorthand for 2>&1 |. This implicit redirection of the standard error is performed after any redirections specified by the command.

There are two formats for redirecting standard output and standard error:




Of the two forms, the first is preferred. This is semantically equivalent to

>WORD 2>&1

The format for appending standard output and standard error is:


This is semantically equivalent to

>>WORD 2>&1

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