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[[Anchor(faq14)]] <<Anchor(faq14)>>
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Redirecting the standard output of a single command is as easy as
{{{
    date > file		 Redirecting the standard output of a single command is as easy as:

{{{#!highlight bash
date > file
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{{{
    date 2> file		 {{{#!highlight bash
date 2> file
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{{{
    date > file 2>&1		 {{{#!highlight bash
date > file 2>&1
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In a loop or other larger code structure:
{{{
    for i in $list; do
        echo "Now processing $i"
        # more stuff here...
    done > 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
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{{{
    # redirect both standard output and standard error to "log.txt"
    exec > log.txt 2>&1
    # all output including stderr now goes into "log.txt"		 {{{#!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"
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Otherwise command grouping helps: (See [[BashFAQ/106|FAQ 106]] for more complex script logging techniques.)
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{{{
    {
     date
     # some other command
     echo done
    } > messages.log 2>&1		 Otherwise, command grouping helps:

{{{#!highlight bash
{
    date
    # some other commands
    echo done
} > messages.log 2>&1
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[[http://wiki.bash-hackers.org/syntax/redirection|More discussion]]

[[http://wiki.bash-hackers.org/howto/redirection_tutorial|In-depth: Illustrated Tutorial]]

----
CategoryShell

How can I redirect the output of multiple commands at once?

Redirecting the standard output of a single command is as easy as: 

   1 date > file

To redirect standard error: 

   1 date 2> file

To redirect both: 

   1 date > file 2>&1

or, a fancier way: 

   1 # Bash only.  Equivalent to date > file 2>&1 but non-portable.
   2 date &> file

Redirecting an entire loop: 

   1 for i in "${list[@]}"; do
   2     echo "Now processing $i"
   3     # more stuff here...
   4 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: 

   1 # redirect both standard output and standard error to "log.txt"
   2 exec > log.txt 2>&1
   3 # all output including stderr now goes into "log.txt"

(See FAQ 106 for more complex script logging techniques.)

Otherwise, command grouping helps: 

   1 {
   2     date
   3     # some other commands
   4     echo done
   5 } > messages.log 2>&1

In this example, the output of all commands within the curly braces is redirected to the file messages.log.

More discussion

In-depth: Illustrated Tutorial

CategoryShell

BashFAQ/014 (last edited 2015-03-05 00:29:41 by izabera)