This is quite a common task for Linux system administrators, when there is need for execution of some command or a local Bash script from a one Linux server or Unix server on another remote Linux machine over SSH.In this article you will find the examples of how to run remote ssh command in Linux to Show result locally.

Basic syntax to run remote ssh command in Linux

$ ssh USER@HOST 'command'

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

Examples:

• Lets say you want to have the mount point details of the remote server.

[root@rhel1 ~]# ssh lradmin@172.31.7.221 df
Filesystem     1K-blocks    Used Available Use% Mounted on
/dev/xvda2      10473452 1599732   8873720  16% /
devtmpfs          489456       0    489456   0% /dev
tmpfs             507736       0    507736   0% /dev/shm
tmpfs             507736   13000    494736   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
[root@rhel1 ~]#

In the above example system will prompt you for the password of your name on remote host. Since we have configured password less ssh between two servers , system performed it without password prompt. In case you want to configure password less ssh between two server please read this article.

• In case you want to have result of uptime command on the remote host.

[root@rhel1 ~]# ssh lradmin@172.31.7.221 uptime
 00:31:26 up 52 min,  2 users,  load average: 0.00, 0.01, 0.04
[root@rhel1 ~]#

• Even you can reboot the server remotely.

[root@rhel1 ~]#ssh root@172.31.7.221 reboot

Run remote ssh command in Linux to Stop or Start any process or service.

• In case you want to stop the httpd process on the remote host.

[root@rhel1 ~]# ssh lradmin@172.31.7.221 'systemctl stop httpd'

Since in the above example command consists of more than one word you need to enclose entire command in quotes ” ‘ “.

• Now to start it again this httpd service use below command.

[root@rhel1 ~]# ssh lradmin@172.31.7.221 'systemctl start httpd'

• Lets check the status of httpd service remotely using below command:

[root@rhel1 ~]# ssh lradmin@172.31.7.221 'systemctl status httpd'
● httpd.service - The Apache HTTP Server
   Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; vendor preset: disabled)
   Active: active (running) since Tue 2017-06-20 00:49:33 EDT; 56s ago
     Docs: man:httpd(8)
           man:apachectl(8)
 Main PID: 2313 (httpd)
   Status: "Total requests: 0; Current requests/sec: 0; Current traffic:   0 B/sec"
   CGroup: /system.slice/httpd.service
           ├─2313 /usr/sbin/httpd -DFOREGROUND
           ├─2314 /usr/sbin/httpd -DFOREGROUND
           ├─2315 /usr/sbin/httpd -DFOREGROUND
           ├─2316 /usr/sbin/httpd -DFOREGROUND
           ├─2317 /usr/sbin/httpd -DFOREGROUND
           └─2318 /usr/sbin/httpd -DFOREGROUND

Jun 20 00:49:33 ip-172-31-7-221.ap-south-1.compute.internal systemd[1]: Starting The Apache HTTP Server...
Jun 20 00:49:33 ip-172-31-7-221.ap-south-1.compute.internal systemd[1]: Started The Apache HTTP Server.
[root@rhel1 ~]#

How to get output in the local Linux file by executing command on remote host.

In case you want to have the output of command executed on the remote host kindly follow below method.

[root@rhel1 ~]# ssh lradmin@172.31.7.221 'free -m' > /tmp/memory.txt
[root@rhel1 ~]# cat /tmp/memory.txt
              total        used        free      shared  buff/cache   available
Mem:            991          81         489          12         420         745
Swap:             0           0           0
[root@rhel1 ~]#

Here in the above example we have executed memory utilisation check command on the remote host and redirected the output of the same to local file “/tmp/memory.txt”. Once done you can check the contents of the file using cat command.

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