How to Run Multiple Background Commands in Bash in a Single Line

How do I run multiple background commands in bash in a single line?

Exactly how do you want them to run? If you want them to be started in the background and run sequentially, you would do something like this:

{ sleep 2; sleep 3; } &

If you want sleep 3 to run only if sleep 2 succeeds, then:

sleep 2 && sleep 3 &

If, on the other hand, you would like them to run in parallel in the background, you can instead do this:

sleep 2 & sleep 3 &

And the two techniques could be combined, such as:

{ sleep 2; echo first finished; } & { sleep 3; echo second finished; } &

Bash being bash, there's often a multitude of different techniques to accomplish the same task, although sometimes with subtle differences between them.

Bash executing multiple commands in background in same line

New answer:
as @CharlesDuffy correctly remarked; my old answer created a subshell, which is entirely unnecessary. In fact the & sign also terminates the line; so no more need to add an extra ;. Bash is complaining because a single line containing only a ; is not a valid command. Bash reads your command as:

cd /scratch/
nohup sh xyz.sh>>del.txt &
;
exit

Therefore you should just remove the ; after your nohup line, and (again; thanks @CharlesDuffy); only call the nohup command if you succeeded to enter the /scratch/ directory; using && means the next command is executed only if the first one succeeds.

cd /scratch/ && nohup sh xyz.sh>>del.txt & exit

Old answer:

You can try putting your command between quotes if you are in a bash shell

cd /scratch/ ; `nohup sh xyz.sh>>del.txt &` ; exit

you can take a look at this question

bash: start multiple chained commands in background

I haven't tested this but how about

print `(touch .file1.lock; cp bigfile1 /destination; rm .file1.lock;) &`;

The parentheses mean execute in a subshell but that shouldn't hurt.

Multiple commands on a single line in Linux

First, if you want to run multiple commands in one line, separate them by a ;:

cmd1 ; cmd2 ; cmd3

The && is the logical and operator. If you issue

cmd1 && cmd2

cmd2 will only run if cmd1 succeeded. That's important to mention (also see below).

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If you use the & to run a command in background simply append the next command without the ; delimiter:

cmd1 & cmd2

The & is not a logical operator in this case, it tells bash to run cmd1 in background.

In your case, the commandline needs syntactically look like this:

killall vsftpd && /usr/sbin/vsftpd & echo "OK"

However, I guess you really meant this:

killall vsftpd ; /usr/sbin/vsftpd & echo "OK"

because otherwise you would not be able to start the process if it is not already running, since killall would return a non zero return code.

Even having this the code is quite fragile. I suggest to use your operating systems facilities to start vsftp as a daemon. I mean facilities like the command start-stop-daemon.

PHP how to run multi bash command in background

I think you also need to handle sleep's stdout/stderr.

( sleep 5 > /dev/null 2>&1; ...; ) &

Or you can put the redirection after ( ... ):

( sleep 5; ffmpeg ...no redir here...; ) < /dev/null > /dev/null 2>&1 &

Run multiple commands, but run the last one in the background

To run one or more commands in a separate process, enclose that series of commands in parentheses. As specified in the Single Unix Specification, §2.9.4 “Compound Commands”:

( compound-list )

Execute compound-list in a subshell environment […]

To group one or more commands in the same shell process, enclose that series of commands in curly braces:

{ compound-list ; }

Execute compound-list in the current process environment. […]

That's true for any POSIX shell (so it also works in Bash).

So your example can be changed to:

sudo mkdir -p /data/db && \
sudo chmod 755 /data/db && \
sudo chown -R addison.pan: /data && \
( mongod & )

That may be good because you want the mongod process separated. On the other hand, a more general answer would be to group the list of commands within the same shell process:

sudo mkdir -p /data/db && \
sudo chmod 755 /data/db && \
sudo chown -R addison.pan: /data && \
{ mongod & }

Both these are described in the above documentation references.

Multiple bash commands in background

ffmpeg will automatically suspend if it doesn't have access to standard out.

You have two choices:

nohup /usr/bin/ffmpeg ... Will take care of the redirect for you, and place the output of ffmpeg in a file called nohup.out

Or add 2>&1>/dev/null after the closing bracket in your argument to exec(). This will send both standard out and standard err to /dev/null.

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