How can I redirect all output to /dev/null?

BashPipeOutput RedirectDev Null

Bash Problem Overview

I want to run a program (google-chrome) in the background, but prevent it from outputting any messages to the terminal.

I tried doing this:

google-chrome 2>&1 1>/dev/null &

However, the terminal still fills up without messages like:

> [5746:5746:0802/100534:ERROR:object_proxy.cc(532)] Failed to call method: org.chromium.Mtpd.EnumerateStorag...

What am I doing wrong? How do I redirect all the output to /dev/null?

Bash Solutions

Solution 1 - Bash

Redirection operators are evaluated left-to-right. You wrongly put 2>&1 first, which points 2 to the same place, as 1 currently is pointed to which is the local terminal screen, because you have not redirected 1 yet. You need to do either of the following:

2>/dev/null 1>/dev/null google-chrome &

Or

2>/dev/null 1>&2 google-chrome &

The placement of the redirect operators in relation to the command does not matter. You can put them before or after the command.

Solution 2 - Bash

In the section Redirection, Bash's reference manual says:

> The operator [n]>&word is used [...] to duplicate output file descriptors

To redirect both standard error and standard output to file you should use the form

&>file

With regard to your case, that means substitute

2>&1 1>/dev/null

with

&>/dev/null

Solution 3 - Bash

It seems that syntax is different:

./a.out 1>/dev/null 2>&1 &

See the devices for FD = 2 are different when ./a.out 1>/dev/null 2>&1 and ./a.out 2>&1 1>/dev/null &

  1. FD=2 points to /dev/null

    >./a.out 1>/dev/null 2>&1 & [1] 21181 >lsof -p pidof a.out COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME a.out 21181 xxxxxxxxxxxxxxx 0u CHR 136,43 0t0 46 /dev/pts/43 a.out 21181 xxxxxxxxxxxxxxx 1w CHR 1,3 0t0 3685 /dev/null a.out 21181 xxxxxxxxxxxxxxx 2w CHR 1,3 0t0 3685 /dev/null

  2. FD=2 points to /dev/pts/43

    >./a.out 2>&1 1>/dev/null & [1] 25955 >lsof -p pidof a.out COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME a.out 25955 xxxxxxxxxxxxxxx 0u CHR 136,43 0t0 46 /dev/pts/43 a.out 25955 xxxxxxxxxxxxxxx 1w CHR 1,3 0t0 3685 /dev/null a.out 25955 xxxxxxxxxxxxxxx 2u CHR 136,43 0t0 46 /dev/pts/43

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Content TypeOriginal AuthorOriginal Content on Stackoverflow
QuestionBenubirdView Question on Stackoverflow
Solution 1 - BashMichael MartinezView Answer on Stackoverflow
Solution 2 - Bashuser1146332View Answer on Stackoverflow
Solution 3 - Bashuser184968View Answer on Stackoverflow