How to Resolve Unix CommandNotFound Error in Python\'s Paramiko Exec_command?

Unix CommandNotFound Error in Paramiko Exec_command

When executing certain Unix commands, such as 'sesu,' through Python's Paramiko exec_command module, you may encounter the "command not found" error. This issue arises because the exec_command method typically does not operate in "login" mode, resulting in a different set of environment variables and startup scripts being sourced compared to a standard interactive SSH session.

Potential Solutions:

1. Specify Full Path to Command:

Use the full path to the command in your exec_command argument. For instance, "/bin/sesu test" instead of "sesu test." You can determine the full path using the "which" command within an interactive SSH session.

2. Adjust Startup Scripts:

Ensure that the startup scripts (e.g., .bash_profile) set the PATH environment variable uniformly for both interactive and non-interactive sessions.

3. Utilize --login Switch:

Run the command using a login shell with the "--login" switch, such as "bash --login -c "sesu test"."

4. Modify Environment Variables in Command:

Modify the environment variables directly within the command itself. In common Unix systems, the following syntax applies: "PATH="$PATH;/path/to/sesu" && sesu test."

5. Force Pseudo Terminal Allocation (Not Recommended):

Enable pseudo terminal allocation for the exec channel using the get_pty=True parameter. However, this approach can lead to unexpected results.

Additional Considerations:

• Similar issues may occur with the LD_LIBRARY_PATH environment variable and the location of shared objects.

• Refer to the following resources for further information:

  • Environment variable differences when using Paramiko
  • Certain Unix commands fail with "... not found" when executed through Java using JSch

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