How should my execl command look in order for it to display "CPU info" in linux command window

Question

I am writing code in C in a Linux terminal trying to display CPU info when the command is run.

execl ( "/bin/lscpu","lscpu",(char*)0);

I have tried everything and can't seem to find the answer that works. This command is giving me a blank and not sure how my execl command should look here.

Does your code continue after the call to to `execl`? If so, you should check `errno` — Emanuel P, Apr 19 '21 at 14:18
no, my code is supposed to end after displaying the information in the terminal — this.mehhh, Apr 19 '21 at 14:20
And have you checked `errno`? What happens when you put the line `perror("exec");` below that line? — Emanuel P, Apr 19 '21 at 14:25
It says "No such file or directory". it makes more sense now. Thanks but do you know what changes I can make to my execl command to get the cpuinfo? — this.mehhh, Apr 19 '21 at 14:34
Try typing `which lscpu` in your terminal. It'll show you where it is (or not in case you don't have it) — Emanuel P, Apr 19 '21 at 14:37
Thank you for all the help. I'm very new to linux and don't understand 1 thing if I write "lscpu" it displays the information that I need but when I tried "which lscpu" it is saying no file or directory.v Which makes sense but don't understand why lscpu is working there in the first place? — this.mehhh, Apr 19 '21 at 14:42
Your shell searches your path (PATH environment variable) to find commands you enter such as lscpu. — ChuckCottrill, Apr 19 '21 at 14:48
Yes, you are correct. Thank you so much. I still don't understand few things about it but I'll eventually figure them out. Thanks I appreciate it — this.mehhh, Apr 19 '21 at 14:48

ChuckCottrill · Answer 1 · 2021-04-19T14:50:21.797

0

Check that the specified path to lscpu is correct,

ls -altr /bin/lscpu

Where is lscpu located?

which lscpu
ls -altr /bin/lscpu /usr/bin/lscpu

Inspect the error returned (the following works),

#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>

int main() {
    int err;
    err = execl( "/bin/lscpu","lscpu",(char*)0 );
    if( err != 0 ) {
        printf("errno=%d: %s\n",errno,strerror(errno));
    }
}

If you replace the pathname (append an 'X'), you will get an error,

err = execl( "/bin/lscpuX","lscpu",(char*)0 );

edited Apr 19 '21 at 14:50

answered Apr 19 '21 at 14:40

ChuckCottrill

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You don't actually have to check the return value. `execl` never returns unless there is an error. – Emanuel P Apr 19 '21 at 14:47
Except that OP had an error, and was blind to the error. – ChuckCottrill Apr 19 '21 at 15:04
Yes, and *if* `execl` returns you should check errors. But it doesn't matter *what* `execl` returns. – Emanuel P Apr 19 '21 at 15:35

How should my execl command look in order for it to display "CPU info" in linux command window

1 Answers1