"command not found" errors in expect script executed by shell script

Question

I am trying to implement "shell script calling expect script" so that it does not prompt the user for entering ssh password every time. I started with Using a variable's value as password for scp, ssh etc. instead of prompting for user input every time and understood that I should have a .sh file and a .exp file. I have expect installed in my system (running expect -v shows expect version 5.43.0).

In my upload-to-server.sh file I have

cd $SOURCE_PATH/shell
./password.exp $DESTINATION_PATH $SSH_CREDENTIALS $PROJECT_INSTALLATION_PATH $PASSWORD

And in my password.exp file I have

#!/usr/bin/expect -f

set DESTINATION_PATH [lindex $argv 0];
set SSH_CREDENTIALS [lindex $argv 1];
set PROJECT_INSTALLATION_PATH [lindex $argv 2];
set PASSWORD [lindex $argv 3];

spawn scp $DESTINATION_PATH/exam.tar $SSH_CREDENTIALS':/'$PROJECT_INSTALLATION_PATH
expect "password:"
send $PASSWORD"\n";
interact

On running the upload-to-server.sh file I get the following error -

./password.exp: line 9: spawn: command not found
couldn't read file "password:": no such file or directory
./password.exp: line 11: send: command not found
./password.exp: line 12: interact: command not found

I arrived at the above code (in the exp file) from multiple sources (without understanding much basics). In one source the code is like this

#!/usr/local/bin/expect
spawn  sftp  -b cmdFile [email protected]
expect "password:"
send "shhh!\n";
interact

Whereas in another source like this

#!/usr/local/bin/expect -f
set TESTCASE_HOME [lindex $argv 0];
set TESTCASE_LIST [lindex $argv 1];
set PASSWORD [lindex $argv 3];

set timeout 200
spawn $TESTCASE_HOME/dobrt -p $TESTCASE_HOME/$TESTCASE_LIST
expect "*?assword:*" {send -- "$PASSWORD\r";}
expect eof

There are some differences there -

• there is an extra -f in the #!/usr/local/bin/expect line

• expect "?assword:" {send -- "$PASSWORD\r";} is different from expect "password:" send "shhh!\n";

• interact replaced with expect eof.

This is my first expect script so don't have much idea what to code. Any pointers?

Thanks,
Sandeepan

Solution

Don't do any of this! You should use public key authentication as the comment above suggests. The way you're going leaves passwords in the clear and is fragile.

Public key authentication is way easier to setup, for example: setup instructions