Bash script to execute a single command over multiple inputs one by one

Question

I have a linux based command named as x2goterminate-session followed by username e.g

x2goterminate-session john

But there are numerous user sessions that I want to terminate in a single go.

slpusrs=`x2golistsessions_root | grep '|S|' | cut -d "|" -f 2`

Above variable slpusrs finds the list of sleeping users and stores them in the slpusrs variable.

Now I want to execute x2goterminate-session command one by one on the list of users, so that all sleeping users are terminated in a single go instead of typing the command followed by user one by one.

command=x2goterminate-session
for i in "${slpusrs[@]}"; do
"$command" "$i"
done

But It isnt working. Please help

Does your command allow multiple usernames, i.e. x2goterminate-session bill john steve sue ? — Mark Setchell
– Mark Setchell, Commented May 11, 2020 at 20:23
@muhammadowaisKhaleeq : You reference slpusrs as array, but you set it as scalar. To set an array variable, you need slpusrs=( $(....) ) — user1934428
– user1934428, Commented May 12, 2020 at 8:17

Barmar · Accepted Answer · 2020-05-11 20:21:17Z

2

slpusrs is a string, not an array. Use

for i in $slpusrs; do
    "$command" $i"
done

answered May 11, 2020 at 20:21

Barmar

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Léa Gris · Accepted Answer · 2020-05-11 22:09:25Z

2

Instead of iterating with Bash, use xargs to run your command for each user.

x2golistsessions_root |
  grep '|S|' |
    cut -d "|" -f 2 |
      xargs -n1 x2goterminate-session

answered May 11, 2020 at 22:09

Léa Gris

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2 Comments

muhammad owais Khaleeq Over a year ago

Thanks!! This worked for me.. Can u please tell that -n1 means only one argument for the command?

Léa Gris Over a year ago

xargs defaults to passing as much arguments as it fiits to a single command call. But since your command may accept only one argument, -n1 tells xargs to pass one argument at a time.

user1934428 · Accepted Answer · 2020-05-12 08:19:31Z

0

If x2goterminate-session realls can work only on one user at a time, you can do a

for user in $(x2golistsessions_root | grep '|S|' | cut -d "|" -f 2)
do
  echo "Murdering unser $user ..."
  x2goterminate-session "$user"
done

No need to introduce a separate variable, unless you need the list of users later on again.

answered May 12, 2020 at 8:19

user1934428

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