External commands cannot directly modify shell variables in the parent shell environment. When an external command is executed, it runs in a separate process, which means it has its own environment. Any changes made to variables within that process do not affect the variables in the parent shell.
However, there are ways to indirectly modify shell variables using external commands:
Command Substitution: You can use command substitution to capture the output of an external command and assign it to a shell variable. For example:
MY_VAR=$(external_command)Output Redirection: You can redirect the output of an external command to a file and then read that file into a shell variable. For example:
external_command > output.txt MY_VAR=$(<output.txt)Sourcing a Script: If an external command is a script that modifies variables, you can source it using the
sourcecommand or the.command. This runs the script in the current shell context:source script.sh
In summary, while external commands cannot modify shell variables directly, you can use techniques like command substitution or sourcing to achieve similar results.
