How can one run multiple programs in the background with single command?

Question

I have tried the commands below, but they do not work.

nohup ./script1.sh & && nohup ./script2.sh &
-bash: syntax error near unexpected token '&&'

nohup ./script1.sh & ; nohup ./script2.sh &
-bash: syntax error near unexpected token ';'

http://stackoverflow.com/questions/14612371/how-do-i-run-multiple-background-commands-in-bash-in-a-single-line — Ciro Santilli OurBigBook.com, Aug 05 '15 at 14:40
I might be missing something obvious, but && implies knowing the exit code of the previous command. If you background it, the exit code won't be known. What was the functional need there? — Richlv, Jan 23 '18 at 13:08

Stéphane Chazelas · Accepted Answer · 2016-11-11T21:33:47.217

32

From a shell syntax point of view, & separates commands like ;/|/&&... (though of course with different semantic). So it's just:

cmd1 & cmd2 & cmd3 &

edited Nov 11 '16 at 21:33

answered Mar 06 '13 at 06:15

Stéphane Chazelas

544,893

1

this is not /quite/ right, ; starts the next command as soon as the first one ended. & actually puts the command to the background.
just try this: echo foo & echo bar & echo test &
– Oluf Lorenzen Mar 06 '13 at 10:08
1

@Finkregh, of course. Nobody doubts that. I just meant they both separate commands (from a syntax point of view) with no implications on how they are run. – Stéphane Chazelas Mar 06 '13 at 10:57
1

It's not quite what was asked, since the question specified issuing a "single command". Neither is my answer, as it too is a series of commands, but it has at least one semantic of a single command in that output is concatenated, can be redirected, etc. – Eli Heady Mar 07 '13 at 00:57
"Multiple commands with a single command" seems to be an oxymoron, though - what does that mean? If this is for something like sudo so you could enter the password only once, wrap then in bash -c or similar. – Richlv Jan 23 '18 at 13:10

Eli Heady · Answer 2 · 2013-03-07T01:11:31.967

12

The bash manpage section titled Compound Commands has two options that would work, list and group commands.

A group command is a series of commands enclosed in curly braces {}. A list is the same, enclosed in parentheses (). Both can be used to background multiple commands within, and finally to background the entire collection as a set. The list construct executes commands in a subshell, so variable assignments are not preserved.

To execute a group of commands:

{ command1 & command2 & } &

You can also execute your commands in a list (subshell):

( command1 & command2 ) &

edited Mar 07 '13 at 01:11

answered Mar 06 '13 at 05:26

Eli Heady

1,234

1

You're welcome. I added the link to the manual. Note that the list () syntax executes the enclosed commands in a subshell, so variables are not preserved within. – Eli Heady Mar 06 '13 at 05:55

score 3 · Answer 3 · answered Mar 06 '13 at 05:19

3

another way:

$(command1 &) && command2 &

answered Mar 06 '13 at 05:19

PersianGulf

10,850

No, it will run first command then after finish first then it will run another command – Rahul Patil Mar 06 '13 at 05:20
you used && in your question, it means at first run a command then if run successfuly, run next command.if you don't consider it, you can run command1 & ; command2 & ; – PersianGulf Mar 06 '13 at 05:24
first command successfully goes in bg, or run using ; no issue with that – Rahul Patil Mar 06 '13 at 05:48

How can one run multiple programs in the background with single command?

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