<<Anchor(faq14)>>
== How can I redirect the output of multiple commands at once? ==
Redirecting the standard output of a single command is as easy as:

{{{#!highlight bash
date > file
}}}

To redirect standard error:
{{{#!highlight bash
date 2> file
}}}

To redirect both:
{{{#!highlight bash
date > file 2>&1
}}}

or, a fancier way:
{{{#!highlight bash
# Bash only.  Equivalent to date > file 2>&1 but non-portable.
date &> file
}}}

Redirecting an entire loop:
{{{#!highlight bash
for i in "${list[@]}"; do
    echo "Now processing $i"
    # more stuff here...
done > file 2>&1
}}}

However, this can become tedious if the output of many programs should be redirected. If all output of a script should go into a file (e.g. a log file), the {{{exec}}} command can be used:

{{{#!highlight bash
# redirect both standard output and standard error to "log.txt"
exec > log.txt 2>&1
# all output including stderr now goes into "log.txt"
}}}

(See [[BashFAQ/106|FAQ 106]] for more complex script logging techniques.)

Otherwise, command grouping helps:

{{{#!highlight bash
{
    date
    # some other commands
    echo done
} > messages.log 2>&1
}}}

In this example, the output of all commands within the curly braces is redirected to the file {{{messages.log}}}.

[[http://wiki.bash-hackers.org/syntax/redirection|More discussion]]

[[http://wiki.bash-hackers.org/howto/redirection_tutorial|In-depth: Illustrated Tutorial]]

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CategoryShell