Implementing a command in C++

[HelloLinux]

how to implement the following in C++

ls -l /proc/$$/exe.

This gives the currently running shell.

[Franklin52]

The easiest way is to use the system() command.
Check the manpage of system.

Regards

[wje_lf]

Franklin52, system() is very useful, but I don't think that's HelloLinux's drift.

HelloLinux, if you do the C++ equivalent of

ls -l /proc/$$/exe

you won't get the currently running shell. You'll get the name of the currently running C++ program.

Which do you want your C++ program to show? The currently running shell, or the currently running C++ program?

[HelloLinux]

It is suggested to avoid usage of System command.

Is there any efficient way of doing it?

[HelloLinux]

I was looking forward to getting the currently running shell, which might have changed from default to some other shell

[wje_lf]

In a C or C++ program, you'll need to get your current pid by using getpid(). Once you have that, you can write a loop in which you repeatedly use the fourth field in /proc/processnumber/stat to get the parent process number. If you get process 1, you've gone too far.

For each time through the loop, you can use readlink() on /proc/processnumber/exe to find the name of the program that process is running.

The first time through the loop that you find that the name of the running program is found in file /etc/shells, that is the name of the shell you are runnning.

I know that you said in a different thread that accessing /proc is time consuming, but the method I outlined is about as efficient as it gets.

Hope this helps.