Detailed explanation of how to pass password to ssh/scp command in bash script

Install SSHPASS

For most recent operating systems, the sshpass package is available in the default package repositories. It can be installed on your system using the following command.

On Debian:

$ sudo apt install sshpass

On CentOS:

$ yum --enablerepo=epel -y install sshpass

Using SSHPASS

sshspass uses the sshspass environment variable to store the user password. You need to first use the sshspass variable and password and then use this command. Below is a simple shell script using sshspass.

export SSHPASS=ry3AvbWO0oupYX9HCMzp0Axx

sshpass -e scp testfile.csv [email protected]:/uploads/

You can also run ssh commands using sshpass as shown below

sshpass -e ssh [email protected]

Solve the problem of SCP command requiring password in shell script

Use a key file.

Here it is assumed that host A (192.168.100.3) is used to obtain the file of host B (192.168.100.4).

Execute the following command on host A to generate a pairing key:

ssh-keygen -t rsa

Press Enter when prompted. The public key is saved in the .ssh directory under the user directory. For example, root is stored in:

/root/.ssh/id_rsa.pub

Copy the id_rsa.pub file in the .ssh directory to the ~/.ssh/ directory of host B and rename it to authorized_keys.

Execute commands on host A to establish trust with host B, for example (assuming the IP of host B is: 192.168.100.4):

scp ~/.ssh/id_rsa.pub 192.168.100.4:/root/.ssh/authorized_keys

Next, you can use the scp and ssh commands to obtain files from host B without a password. ssh 192.168.100.4 Press Enter and no password is required.

Note: Actually, just add the content of id_rsa.pub to the authorized_keys of the other machine.