如何从Linux上运行的进程的命令行发出命令

Question

Lets say I issue a command from the Linux command line. This will cause Linux to create a new Process and lets say that the Process expects to receive the command from the user.

For Example: I will run a python script test.py which will accept a command from the user.

$python test.py

TEST>addController(192.168.56.101)

Controller added

TEST>

The question I have is can I write a script which will go into the command line (TEST>) and issue a command? As far as I know if I write a script to run multiple commands it will wait for the first process to exit before running the next command.

Regards,

Vinay Pai BH

Answer 1

You should look into expect . It's a tool that is designed to automate user interaction with commands that need it. The man page explains how to use it.

Seems like there is also pexpect , a Python version of similar functionality.

Answer 2

Assuming the Python script is reading its commands from stdin, you can pass them in with a pipe or a redirection:

$ python test.py <<< 'addController(192.168.56.101)'

$ echo $'addController(192.168.56.101)\nfoo()\nbar()\nbaz()' | python test.py

$ python test.py <<EOF
addController(192.168.56.101)
foo()
bar()
baz()
EOF

Answer 3

If you don't mind waiting for the calls to finish (one at a time) before returning control to your program, you can use the subprocess library. If you want to start something running and not wait for it to finish, you can use the multiprocessing library.