Forcing the environment to bash when executing shell command in C++ - c++

Question

I'm creating an application in C++ that can execute some commands shell to get informations about the system. The problem occurs when I use in my script code something like [[ "$devname" == "bus/"* ]]&& continue;, executing this command returns error, probably because when executing the sheel script the environment are in dash instead of bash. I tried to execute the command with #!/usr/bin/env bash but don't work. The full command is hardcoded inline and I'm avoiding the use of a shell script file.

Answer 1

If you have a command like this, say:
[[ "$devname" == "bus/"* ]] && hostname || echo "no"
You can run it this way:
bash -c '[[ "$devname" == "bus/"* ]] && hostname || echo "no"'
So if you just build one string that contains the above, you can run it using popen() or whatever. In C++ you'll have to escape the inner quotes if you use the above literally, so:
const char* command = "bash -c '[[ \"$devname\" == \"bus/\"* ]] && hostname || echo \"no\"'";

Answer 2

You have two options:
1) Explicitly set SHELL via putenv():
putenv("SHELL=/bin/bash");
execl(...);
2) Explicitly execute /bin/bash, instead of relying on the hashbang:
execl("/bin/bash", script.c_str(), NULL);
// script is the script you're trying to execute.