Databases, Systems & Networks

Source: nixCraft

I have a backup sync program on local server. I have an ssh password less login set up, and I can run commands on an external server in bash script doing:

ssh root@server2 "sync; sync; /sbin/shutdown -h now"

How do I run multiple commands in bash on a remote Unix or Linux server? What is the best Way to SSH in and Run various unix commands in bash?

There are various ways to run multiple commands on a remote Unix server. The syntax is as follows:

Simple bash syntax to run multiple commands on remote machine

Simply run command2 if command1 successful on a remote host called foo
$ ssh bar@foo "command1 && command2"
Run date and hostname commands:
$ ssh user@host "date && hostname"
You can run sudo command as follows on a remote box called server1.cyberciti.biz:
$ ssh -t vivek@server1.dbsysnet.com "sudo /sbin/shutdown -h now"
And, finally:
$ ssh root@server1.dbsysnet.com "sync && sync && /sbin/shutdown -h now"

Bash here document syntax

The here document syntax tells the shell to read input from the current source (HERE) until a line containing only word (HERE) is seen:

ssh server1 << HERE
 command1
 command2
HERE

Here is another example to run a multiple commands on a remote system:

ssh vivek@server1.dbsysnet.com << EOF
 date
 hostname
 cat /etc/resolv.conf
EOF

With sudo command type:

ssh -t vivek@server1.dbsysnet.com << EOF
 sync
 sync
 sudo /sbin/shutdown -h 0
EOF

Pipe script to a remote server

Finally, create a script called « remote-box-commands.bash » as follows on your local server:

date
hostname
cat /etc/resolv.conf

Run it as follows on a remote server called nas02nixcrafthomeserver:
$ cat remote-box-commands.bash | ssh user@nas02dbsysnet
OR
cat remote-box-commands.bash | ssh -t vivek@nas02dbsysnet

Please note that the -t option will get rid of « Sorry, you must have a tty to run sudo/insert your-command-here » error message. For more info see your ssh and bash command man page.