CODEWITHSUNDEEP
c++clinuxubuntu
RoboAlex
RoboAlex

Reputation: 5015

Create a file as executable program in C in Ubuntu

My program receives an executable binary file through a TCP socket.

I need to save this file in to the harddisk as a executable program. File is successfully received but the problem is the default file attribute is being set to non executable.

How to change the file's attribute as executable in C in Ubuntu?

Thank you, Regards, Robo

Upvotes: 2

Views: 1127

Answers (3)

ephemient
ephemient

Reputation: 204994

How are you creating and writing the file? If you know it's going to be executable, just make the file with the correct mode in the first place.

int fd = open("path/to/file", O_WRONLY | O_CREAT, 0777);

Unless umask is stripping the executable bits (common values are 0022 and 0002 which leave the executable bits alone), path/to/file will be created initially executable.

Upvotes: 3

dschulz
dschulz

Reputation: 4816

How about int chmod(const char *path, mode_t mode) and int fchmod(int fd, mode_t mode) ? 

apropos chmod
man 2 chmod

The most basic example:

#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char* argv[]){

   char * fpath = "/path/to/binary";
   int ret=0;
   if(ret = chmod(fpath, S_IRUSR|S_IXUSR) < 0){
      perror("chmod failed");
      exit(1);
   }

   printf("chmod ok\n");
   exit(0);
}

Upvotes: 5

Summer_More_More_Tea
Summer_More_More_Tea

Reputation: 13446

You can change the file mode with chmod. Read the man page(man 2 chmod) for detail(roughly the same as shell command chmod).

Upvotes: 2

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