using watch run 2 commands

Question

I have to do watch two commands in the same terminal windows. I mean something like

watch du -h filename.txt && df -h

But its showing only one output.

So what I am thinking is may be its not possible to use watch to run multiple commands on the same window.

If there is any way , Please let me know.

Thank you.

score 142 · Accepted Answer · answered Mar 12 '15 at 12:41

142

You can quote the commands:

watch "du -h filename.txt && df -h"

And they'll be executed together.

answered Mar 12 '15 at 12:41

Oli

299,936

Thanks Oli. actually office PC so not daring to do experiments. so posted here for sure solution. Thank you. – Raja G Mar 12 '15 at 13:18
Hey you sure they will work ? because when execute I am getting some permission denied error" df: `/usr/raja/hostctrl/new': Permission denied " – Raja G Mar 12 '15 at 13:24
That seems to be a separate issue. You'd see that issueeven without it being wrapped in watch. – Oli Mar 12 '15 at 20:56
4

Be aware this works because those example commands return with true. Should the first command return false the second command wouldn't be executed (because of boolean evaluation shortcut) – karatedog Mar 20 '16 at 13:31
3

FTR, my command uses && because the OP uses &&. The combination of commands and their linking is incidental to the answer. – Oli Jul 01 '17 at 16:52
watch "du -h filename.txt ; df -h gets around the problem karatedog mentioned. Further reading: https://stackoverflow.com/questions/13077241/execute-combine-multiple-linux-commands-in-one-line – Monty _s Flying Circus Apr 20 '18 at 16:44

score 36 · Answer 2 · answered Jun 10 '16 at 19:15

36

If you want to make sure both commands execute, one of the ways is to separate them with ; instead of &&.

watch 'du -h filename.txt; df -h'

&& allows the execution of second command (second operand, to the right of &&) only if the first command executed successfully (exit status 0). If this is intended behaviour, go with &&.

answered Jun 10 '16 at 19:15

pranavcode

461

3

This semicolon form seems best to me as an answer to the original question. If you want to "run two commands", use a semicolon! If you want to "run one command, then maybe another" use && .... – JeremyDouglass Jul 28 '18 at 22:11

Geofferey · Answer 3 · 2017-10-31T01:03:16.150

8

For completeness sake...

 watch 'du -h filename.txt || true && df -h'

The '|| true' part causes the first command to evaluate as true even if it fails for some reason. This will allow the next command after the && to execute no matter the output of first. This is most likely unnecessary for the scenario, just showing it to be possible.

edited Oct 31 '17 at 01:03

answered Oct 31 '17 at 00:57

Geofferey

181

1

could || true && be replaced with a single ;? – wotanii Jun 22 '22 at 11:20
@wotanii yes, you could just use ;. – guettli Apr 04 '23 at 06:30

score 2 · Answer 4 · answered May 07 '19 at 10:11

2

For multiple commands to run simultaneously, use single & operator between the commands. Like:

dothis & dothat

To clear any confusion, here's how different operators work:

c1 & c2  # Run both commands parallelly
c1 ; c2  # Run both commands one by one
c1 && c2 # Run c2 only if c1 exits successfully
c1 || c2 # Run c2 only if c1 fails

answered May 07 '19 at 10:11

Vibhum Bhardwaj

83

c1 & c2 will not run both commands parallel, if c1 is successful run then only c2 will run. – Raja G May 07 '19 at 11:38
2

Actually running 'c1 & c2' what it does is run c1 in background and run c2. You can test it out yourself: (exit 1) && echo "Success" will not print "Success", while (exti 1) & echo "Success" will print "Success" – Kerruba Feb 03 '21 at 09:20
1

This gave me some insights that I appreciated, therefore upvoting. – Rojan Gh. Sep 10 '21 at 08:48

using watch run 2 commands

4 Answers4