Awesome way to run-execute multiple remote commands-shell scripts using ssh in Linux / UNIX.

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In my previous article , we have discussed about how we can execute remote command over ssh in Linux/Unix. What if we want to execute multiple commands or shell script? In this article we will be discussing about how to run-execute multiple remote commands-shell scripts using ssh in Linux / UNIX.

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Now you are very much aware about executing single remote command using ssh as below:

# ssh lradmin@172.31.7.221 df

Syntax to run-execute multiple remote commands-shell scripts using ssh

ssh USER@HOST 'command1';'command2';'command2';....;'commandN'

Here:

ssh –> is the protocol or command being used for making connection with remote server.

USER –> is the username on remote server.

HOST –> is the remote host on which you want to execute remote command.

Command –> are the commands that you want to execute on remote host.

• Simple Multiple remote commands using ssh

Lets say you want to have the output of df command and uptime command in one go, then follow below command:

[root@rhel1 ~]# ssh lradmin@172.31.7.221 df;uptime
Filesystem     1K-blocks    Used Available Use% Mounted on
/dev/xvda2      10473452 1581544   8891908  16% /
devtmpfs          489456       0    489456   0% /dev
tmpfs             507736       0    507736   0% /dev/shm
tmpfs             507736   12972    494764   3% /run
tmpfs             507736       0    507736   0% /sys/fs/cgroup
tmpfs             101548       0    101548   0% /run/user/1000
tmpfs             101548       0    101548   0% /run/user/0
 00:25:16 up 16 min,  1 user,  load average: 0.00, 0.01, 0.04
[root@rhel1 ~]#

• Conditional Multiple remote commands using ssh

You can even execute conditional flow described in this article. For example you want to execute second command only if first command is successfully executed.

[root@rhel1 ~]# ssh lradmin@172.31.7.221 'mkdir /tmp/data && cd /tmp/data'

Here in this case second command “cd” is executed remotely only if mkdir command executed successfully.  Please make sure you enclose your multiple commands in  quotes ” ‘ “.

• Remote sudo commands using ssh

Even you can execute remote commands using sudo facility available in Linux as below:

[root@rhel1 ~]# ssh -t manmohan@172.31.7.221 "sudo ls -al /root"
[sudo] password for manmohan:
total 44
dr-xr-x---.  4 root root 4096 Jun 12 12:08 .
dr-xr-xr-x. 19 root root 4096 Jun 12 10:35 ..
-rw-------.  1 root root 7548 Mar  1  2016 anaconda-ks.cfg
-rw-------.  1 root root 2780 Jun 20 01:23 .bash_history
-rw-r--r--.  1 root root   18 Dec 28  2013 .bash_logout
-rw-r--r--.  1 root root  176 Dec 28  2013 .bash_profile
-rw-r--r--.  1 root root  176 Dec 28  2013 .bashrc
-rw-r--r--.  1 root root  100 Dec 28  2013 .cshrc
-rw-------.  1 root root   62 Jun 12 10:35 .passwd-s3fs
drwxr-----.  3 root root   18 Jun 12 10:21 .pki
drwx------.  2 root root   28 Jun 12 10:11 .ssh
-rw-r--r--.  1 root root  129 Dec 28  2013 .tcshrc
Connection to 172.31.7.221 closed.

Note: Make sure you include “-t” option since sudo requires interactive shell , Otherwise you will get below message:

[root@rhel1 ~]# ssh  manmohan@172.31.7.221 "sudo ls -al /root"
sudo: sorry, you must have a tty to run sudo
[root@rhel1 ~]#

• Multiple remote commands using Here doc

Another awesome method for executing multiple remote commands is using “Here document”.In this we enclose our list of commands within a tag word like “HERE” in the below example. Basically it signifies start and stop of the commands.

Basic Syntax:

ssh USER@SERVER << HERE
 command1
 command2
HERE

Basically in this type we enclose our commands withing two common words. In the above syntax we have used “HERE” for indicating start and stop of commands.

Example:

[root@rhel1 ~]# ssh -T lradmin@172.31.7.221 << HERE
uptime
free -m
date
HERE

 01:14:47 up  1:05,  1 user,  load average: 0.00, 0.01, 0.05
              total        used        free      shared  buff/cache   available
Mem:            991          76         779          12         136         774
Swap:             0           0           0
Wed Jun 21 01:14:47 EDT 2017
[root@rhel1 ~]#

In above example we have used “-T” option to remove the “Pseudo-terminal will not be allocated because stdin is not a terminal.” message during execution.

Another example:

[root@rhel1 ~]# ssh -T lradmin@172.31.7.221 << MYCOMMANDS
w
df -h
hostname
MYCOMMANDS

 01:17:38 up  1:08,  1 user,  load average: 0.00, 0.01, 0.05
USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT
ec2-user pts/1    43.242.225.117   00:23   12:34   0.12s  0.19s sshd: ec2-user [priv]
Filesystem      Size  Used Avail Use% Mounted on
/dev/xvda2       10G  1.6G  8.5G  16% /
devtmpfs        478M     0  478M   0% /dev
tmpfs           496M     0  496M   0% /dev/shm
tmpfs           496M   13M  484M   3% /run
tmpfs           496M     0  496M   0% /sys/fs/cgroup
tmpfs           100M     0  100M   0% /run/user/1000
tmpfs           100M     0  100M   0% /run/user/0
ip-172-31-7-221.ap-south-1.compute.internal
[root@rhel1 ~]#

• Multiple remote commands using Bash Script over ssh

You can also run-execute multiple remote commands within a bash script.  Here first need to write a local bash script as below:

[root@rhel1 ~]# cat myscript.sh
free -m
date
hostname
uptime
[root@rhel1 ~]#

Now Execute this local bash shell script using below method on remote Linux server as below:

[root@rhel1 ~]# ssh lradmin@172.31.7.221 'bash -s' < myscript.sh
              total        used        free      shared  buff/cache   available
Mem:            991          75         779          12         136         774
Swap:             0           0           0
Wed Jun 21 01:25:38 EDT 2017
ip-172-31-7-221.ap-south-1.compute.internal
 01:25:38 up  1:16,  1 user,  load average: 0.00, 0.01, 0.05
[root@rhel1 ~]#

In this way we can run-execute multiple remote commands-shell scripts using ssh on Linux/Unix server.

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