execle - Linux

Overview

execle is a system call that replaces the current running program with a new program. It is typically used in conjunction with the fork() system call to create new processes.

Syntax

int execle(const char *path, const char *arg0, ..., const char *argn, (char *)0);

• path: The path to the new program to execute.
• arg0: The name of the new program.
• …, argn: Optional arguments to pass to the new program.
• *(char )0: A null pointer to terminate the list of arguments.

Options/Flags

• None

Examples

Simple example:

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int main() {
    execle("/bin/ls", "ls", "-l", NULL);
    // If execle succeeds, this line will not be executed.
    perror("execle");
    exit(EXIT_FAILURE);
}

Complex example:

This example creates a new process that runs the ls command with the -l and -a arguments.

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int main() {
    char *args[] = {"/bin/ls", "-l", "-a", NULL};
    execle(args[0], args[0], args[1], args[2], NULL);
    // If execle succeeds, this line will not be executed.
    perror("execle");
    exit(EXIT_FAILURE);
}

Common Issues

• Permission denied: Ensure that the user has permission to execute the new program.
• File not found: Verify that the path to the new program is correct.
• Invalid arguments: Check that the arguments passed to the new program are valid.

Integration

• fork() and execle(): Fork creates a new process and execle replaces the current process with a new program. This is a common technique for creating new processes.
• Pipes: Pipes can be used to connect the output of one program to the input of another program. Execle can be used to launch a new program that reads from or writes to a pipe.

Related Commands

• fork
• exec
• execlp
• execv
• execvp