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This article shows you how to run Linux commands remotely through SSH. The content is concise and easy to understand. It will definitely brighten your eyes. I hope you can get something through the detailed introduction of this article.

We may sometimes need to run commands on remote machines. If it is only an occasional operation, to achieve this, you can log in to the remote system and execute the command directly. But it's a little annoying to do it every time. In that case, is there a better way to get rid of this troublesome operation?

How did this happen? SSH allows you to run commands on a remote computer without logging in to it.

The general syntax is as follows:

$ssh [user name] @ [remote hostname or IP] [command or script]

1. How to run commands on a remote Linux system through SSH

The following example allows the user to run the df command on a remote Linux machine through ssh.

$ssh daygeek@CentOS7.2daygeek.com df-h Filesystem Size Used Avail Use% Mounted on / dev/mapper/centos-root 27G 4.4G 23G 17% / devtmpfs 903M 0903M 0% / devtmpfs 920M 0920m 0% / dev/shm tmpfs 920M 9.3M 910m 2% / run tmpfs 920m 0920m 0% / sys/fs/cgroup / dev/sda1 1014M 179M 836M 18% / boot tmpfs 184M 8.0K 184m 1% / run/user/42 tmpfs 184M 0 184m 0% / run/user/1000

2. How to run multiple commands on a remote Linux system through SSH

The following example allows the user to run more than one command at a time on a remote Linux machine through ssh.

Run both the uptime command and the free command on the remote Linux system.

$ssh daygeek@CentOS7.2daygeek.com "uptime & & free-m" 23:05:10 up 10 min, 0 users, load average: 0.00,0.03,0.03 total used free shared buffers cached Mem: 1878 432 1445 1100 134-/ + buffers/cache: 197 1680 Swap: 3071 0 3071

3. How to run a command with sudo permission on a remote Linux system through SSH

The following example allows a user to run a fdisk command with sudo privileges on a remote Linux machine through ssh.

Ordinary users are not allowed to execute commands provided in the system binary (/ usr/sbin/) directory. The user needs root permission to run it.

So you need root permission to run fdisk commands on Linux systems. The which command returns the full executable path of a given command.

$which fdisk / usr/sbin/fdisk$ ssh-t daygeek@CentOS7.2daygeek.com "sudo fdisk-l" [sudo] password for daygeek: Disk / dev/sda: 32.2 GB, 32212254720 bytes 62914560 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I size O size (minimum/optimal): 512 bytes / 512 bytes Disk label type: dos Disk identifier: 0x000bf685 Device Boot Start End Blocks Id System / dev/sda1 * 2048 2099199 1048576 83 Linux / dev/sda2 2099200 62914559 30407680 8e Linux LVM Disk / dev/sdb: 10.7 GB, 10737418240 bytes 20971520 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes GB O size (minimum/optimal): 512 bytes / 512 bytes Disk / dev/mapper/centos-root: 29.0 GB, 28982640640 bytes, 56606720 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I size (minimum/optimal): 512 bytes / 512 bytes Disk / dev/mapper/centos-swap: 2147 MB, 2147483648 bytes 4194304 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I size O size (minimum/optimal): 512 bytes / 512 bytes Connection to centos7.2daygeek.com closed.

4. How to run the service control command with sudo authority on the remote Linux system through SSH

The following example allows users to run service control commands with sudo privileges on a remote Linux machine through ssh.

$ssh-t daygeek@CentOS7.2daygeek.com "sudo systemctl restart httpd" [sudo] password for daygeek: Connection to centos7.2daygeek.com closed.

5. How to run commands on a remote Linux system through a non-standard port SSH

The following example allows users to run hostnamectl commands through ssh on remote Linux machines that use non-standard ports.

$ssh-p 2200 daygeek@CentOS7.2daygeek.com hostnamectl Static hostname: Ubuntu18.2daygeek.com Icon name: computer-vm Chassis: vm Machine ID: 27f6c2febda84dc881f28fd145077187 Boot ID: bbeccdf932be41ddb5deae9e5f15183d Virtualization: oracle Operating System: Ubuntu 18.04.2 LTS Kernel: Linux 4.15.0-60-generic Architecture: x86-64

6. How to save the output of the remote system to the local system

The following example allows the user to run top commands on a remote Linux machine through ssh and save the output to the local system.

$ssh daygeek@CentOS7.2daygeek.com "top- bc | head-n 35" > / tmp/top-output.txtcat / tmp/top-output.txt top- 01:13:11 up 18 min, 1 user, load average: 0.01,0.05,0.10 Tasks: 168total, 1 running, 167sleeping, 0 stopped, 0 zombie% Cpu (s): 0.0 us, 6.2 sy, 0.0 ni, 93.8 id, 0.0 wa, 0.0 hi, 0.0 si 0.0 st KiB Mem: 1882300 total, 1176324 free, 342392 used, 363584 buff/cache KiB Swap: 2097148 total, 2097148 free, 0 used. 1348140 avail Mem PID USER PR NI VIRT RES SHR S% CPU% MEM TIME+ COMMAND 4943 daygeek 200 162052 2248 1612 R 10.0 0.1 daygeek 00.07 top-bc 1 root 20 128276 6936 4204 S 0.0 0.4 MEM TIME+ COMMAND 03.08 / usr/lib/sy+ 2 root 20 00 00 S 0.0 0.00 [kthreadd] 3 root 20 00 00 S 0.0 0.00: 00.25 [ksoftirqd/+ 4 root 20 00 00 S 0.0 0.00: 00.00 [kworker/0:+ 5 root 0-20 000 S 0.0 0.00: 00.00 [kworker/0:+ 7 root rt 00 00 S 0.0 0.00: 00.00 [migration/+ 8 root 20 00 S 0.0 0.00: 00.00 [rcu_bh] 9 root 20 00 00 S 0.0 0.00: 00.77 [rcu_sched] 10 root 0-20 000 S 0.00. 00: 00.00 [lru-add-dr+ 11 root rt 00 00 S 0.0 0.00: 00.01 [watchdog/0] 13 root 20 00 00 S 0.0 0.00: 00.00 [kdevtmpfs] 14 root 0-20 000 S 0.0 0.00: 00.00 [netns] 15 root 20 00 S 0.0 0.00: 00.00 [khungtaskd] 16 root 0-20 000 S 0.0 0.00: 00.00 [writeback] 17 root 0-20 000 S 0.0 0.00: 00.00 [kintegrity+ 18 root 0-20 000 S 0 .00.00: 00.00 [bioset] 19 root 0-20 000 S 0.0 0.00: 00.00 [bioset]

Or you can run multiple commands on a remote system using the following format:

$ssh daygeek@CentOS7.2daygeek.com hostnamectlfree-mgrep daygeek / etc/passwdEO

The output of the above command is as follows:

Pseudo-terminal will not be allocated because stdin is not a terminal. Static hostname: CentOS7.2daygeek.com Icon name: computer-vm Chassis: vm Machine ID: 002f47b82af248f5be1d67b67e03514c Boot ID: dca9a1ba06374d7d96678f9461752482 Virtualization: kvm Operating System: CentOS Linux 7 (Core) CPE OS Name: cpe:/o:centos:centos:7 Kernel: Linux 3.10.0-957.el7.x86_64 Architecture: x86-64 total used free shared buff / cache available Mem: 1838 335 1146 11 355 1314 Swap: 2047 0 2047 daygeek:x:1000:1000:2daygeek:/home/daygeek:/bin/bash

7. How to run local Bash scripts on remote systems

The following example allows the user to run the local bash script remote-test.sh on a remote Linux machine through ssh.

Create a shell script and execute it.

$vi / tmpax remoteltel test.shallows hostnamectl. Binram Basil name: remote-test.sh#- uptime free-m df-h uname-a hostnamectl

The output of the above command is as follows:

$ssh daygeek@CentOS7.2daygeek.com 'bash-s' 01:17:09 up 22 min, 1 user, load average: 0.00,0.02 Total used free shared buff/cache available Mem: 1838 333 1148 11 355 1316 Swap: 2047 2047 Filesystem Size Used Avail Use% Mounted on / dev/mapper/centos-root 27G 4.4G 23G 17% / devtmpfs 903M 0903M 0% / devtmpfs 920m 0920m 0% / dev/shm tmpfs 920M 9.3M 910m 2% / run tmpfs 920M 0920M 0% / sys/fs/cgroup / dev/sda1 1014M 179M 836M 18% / boot tmpfs 184M 12K 184M 1% / run/user/42 tmpfs 184M 0 184M 0 % / run/user/1000 Linux CentOS7.2daygeek.com 3.10.0-957.el7.x86_64 # 1 SMP Thu Nov 8 23:39:32 UTC 2018 x86 "64 GNU/Linux Static hostname: CentOS7.2daygeek.com Icon name: computer-vm Chassis: vm Machine ID: 002f47b82af248f5be1d67b67e03514c Boot ID: dca9a1ba06374d7d96678f9461752482 Virtualization: kvm Operating System: CentOS Linux 7 (Core) CPE OS Name: cpe : / o:centos:centos:7 Kernel: Linux 3.10.0-957.el7.x86_64 Architecture: x86-64

Or you can use pipes. If you think the output doesn't look good, make some changes to make it more elegant.

$vi / tmpCompact RemoteMustMuth1.shemeasure binder Basiple name: remote-test.sh echo "- System Uptime----" uptime echo-e "\ n" echo "- Memory Usage- -- "free-m echo-e"\ n "echo"-Disk Usage--- "df-h echo-e"\ n "echo"- -Kernel Version--- "uname-an echo-e"\ n "echo"-HostName Info---- "hostnamectl echo" -"

The output of the above script is as follows:

$cat / tmp/remote-test.sh | ssh daygeek@CentOS7.2daygeek.com Pseudo-terminal will not be allocated because stdin is not a terminal. -System Uptime---- 03:14:09 up 2:19, 1 user, load average: 0.00,0.01 Memory Usage- total used free shared buff/cache available Mem: 1838 376 1063 11 398 1253 Swap: 2047 0 20- -Disk Usage--- Filesystem Size Used Avail Use% Mounted on / dev/mapper/centos-root 27G 4.4G 23G 17% / devtmpfs 903M 0903M 0% / devtmpfs 920m 0 920m 0% / dev/shm tmpfs 920M 9.3M 910m 2% / run tmpfs 920M 0920M 0% / sys/fs/cgroup / dev/sda1 1014M 179M 836M 18% / boot tmpfs 184M 12K 184m 1% / run/user/42 tmpfs 184M 0 184M 0 / run/user/1000 tmpfs 184M 0 184M 0% / run/user/0-Kernel Version--- Linux CentOS7.2daygeek.com 3.10.0-957.el7.x86_64 # 1 SMP Thu Nov 8 23:39:32 UTC 2018 x 86 million 64 X86'64 x86'64 GNU/Linux-HostName Info---- Static hostname: CentOS7.2daygeek.com Icon name: computer-vm Chassis: vm Machine ID: 002f47b82af248f5be1d67b67e03514c Boot ID: dca9a1ba06374d7d96678f9461752482 Virtualization: kvm Operating System: CentOS Linux 7 (Core) CPE OS Name: cpe:/o:centos:centos:7 Kernel: Linux 3.10.0-957.el7.x86_64 Architecture: x86-64

How to run multiple instructions on multiple remote systems at the same time

The following bash script allows users to run multiple instructions on multiple remote systems at the same time. Using a simple for loop implementation.

To do this, you can try the PSSH command or ClusterShell command or DSH command.

$vi / tmp/multiple-host.sh for host in CentOS7.2daygeek.com CentOS6.2daygeek.com do ssh daygeek@$ {host} "uname-a _ uptime _ date _ exchange _ w" done

The output of the above script is as follows:

$sh multiple-host.sh Linux CentOS7.2daygeek.com 3.10.0-957.el7.x86_64 # 1 SMP Thu Nov 8 23:39:32 UTC 2018 x86 "64 GNU/Linux 01:33:57 up 39 min, 1 user, load average: 0.07,0.06,0.06 Wed Sep 25 01:33:57 CDT 2019 01:33:57 up 39 min, 1 user, load average: 0.07,0.06 0.06 USER TTY FROM daygeek@CentOS7.2daygeek.com IDLE JCPU PCPU WHAT daygeek pts/0 192.168.1.6 01:08 23:25 0.06s-bash Linux CentOS6.2daygeek.com 2.6.32-754.el6.x86_64 # 1 SMP Tue Jun 19 21:26:04 UTC 2018 x86 "64 GNU/Linux 23:33:58 up 39 min, 0 users, load average: 0.00,0.00 0.00 Tue Sep 24 23:33:58 MST 2019 23:33:58 up 39 min, 0 users, load average: 0.00, 0.00, 0.00 USER TTY FROM daygeek@CentOS7.2daygeek.com IDLE JCPU PCPU WHAT

9. How to add a password using the sshpass command

If you find it troublesome to enter a password every time, I suggest you choose one of the following methods to solve the problem depending on your needs.

If you often do something like this, I recommend that you set up password-free authentication, as it is a standard and permanent solution.

If you only perform these tasks a few times a month, I recommend you use the sshpass tool. Just use the-p parameter option to provide your password.

$sshpass-p 'enter your password' ssh-p 2200 daygeek@CentOS7.2daygeek.com ip a 1: lo: mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1 link/loopback 0000 scope host valid_lft forever preferred_lft forever 0000 brd 0000 00 scope host valid_lft forever preferred_lft forever 0000 inet 127.0.0.1 scope host lo valid_lft forever preferred_lft forever inet6:: 1 scope host lo valid_lft forever preferred_lft forever inet6 128 scope host valid_lft forever preferred_lft forever 2: Eth0: mtu 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether 08 brd ff:ff:ff:ff:ff:ff inet 1500 qdisc pfifo_fast state UP group default qlen 1000 link/ether 08 VLV 27F brd ff:ff:ff:ff:ff:ff inet 192.168.1.12 Linux system Linux is a free one. UNIX-like operating system that uses and spreads freely Is a POSIX-based multi-user, multi-tasking, multi-threaded and multi-CPU operating system, using Linux to run major Unix tools, applications and network protocols.

The above is how Linux commands run remotely through SSH. Have you learned any knowledge or skills? If you want to learn more skills or enrich your knowledge reserve, you are welcome to follow the industry information channel.

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