CODEWITHSUNDEEP
cpath
Todd Hainsworth
Todd Hainsworth

Reputation: 114

Checking a different directory for a Program

So I am working on a small project and I have this function:

void call_execve(char *cmd)
{
    int i;
    char bin[5];
    char full_cmd[100];

    strcpy(bin, "/bin/");

    strcat(full_cmd, bin);
    strcat(full_cmd, cmd);

    if(fork() == 0) {
        i = execve(full_cmd, my_argv, my_envp);
        if(i < 0) {
            printf("%s: %s\n", full_cmd, "command not found");
            exit(1);        
        }
    } else {
        wait(NULL);
    }
}

I guess my brain just isn't thinking tonight, I need to make it check the /usr/bin directory for the program or shell command.

I know I can use the $PATH variable, but I am unsure how to work with it via the C Language. It would be great if you could re-write this function to either execute the program from the /usr/bin directory or use $PATH to execute the program

Thank you in advance.

GeissT.

Upvotes: 0

Views: 93

Answers (2)

Basile Starynkevitch
Basile Starynkevitch

Reputation: 1

The execvp library function mimics the shell search inside $PATH and then call execve.

If you want on the contrary to execute a program whose file path is known to you (e.g. /usr/bin/mail) then just call execve with the complete path as the first filename argument.

Upvotes: 0

Ignacio Vazquez-Abrams
Ignacio Vazquez-Abrams

Reputation: 799390

From the exec(3) man page:

The execlp(), execvp(), and execvpe() functions duplicate the actions of the shell in searching for an executable file if the specified file‐ name does not contain a slash (/) character. The file is sought in the colon-separated list of directory pathnames specified in the PATH environment variable.

Upvotes: 1

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