Which shell will execute the cmd when popen is called

Question

First of all, forgive my awful english.....

This is the prototype

FILE *popen(const char* cmd_string, const char* type);

Here is my question, the book says that when popen function is called, it will call exec to get a shell to execute the cmd_string we give to popen, but I'm not sure which shell will exec get, so can anyone give me an answer?

score 2 · Answer 1 · answered Nov 19 '18 at 15:42

2

/bin/sh : From the doc:

   The command argument is a pointer to a null-terminated string
   containing a shell command line.  This command is passed to /bin/sh
   using the -c flag; interpretation, if any, is performed by the shell.

answered Nov 19 '18 at 15:42

Maksim

511
5
15

score 0 · Accepted Answer · answered Nov 19 '18 at 16:01

0

Let's try and see:

$ cat test.c
#include <stdio.h>

int main() {

  FILE *fp;
  char var[5];

  fp = popen("echo $0", "r");
  fgets(var, 5, fp);
  printf("%s", var);
}
$ gcc -Wall test.c
$ ./a.out
sh

answered Nov 19 '18 at 16:01

James Brown

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7
43
59

1

Thank you very much, I understood now, it's really helpful, thank you again – anonymous Nov 19 '18 at 17:03

Which shell will execute the cmd when popen is called

2 Answers2