Re: chmod

[Corrin Lakeland <lakeland@cs.otago.ac.nz>]

> > And if anyone's in a 'splaining mood, here's another one: how do you set
> > all files so that the group permissions match the user permissions?
>
> This one is tougher, I think.  You could write
> such a utility pretty easily in C using the "stat()" function, but
> even though it's simple it seems like over kill. Gotta be a better
> way.

Doing it in C (untested code):

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>

int main(int argc, char * argv[]) {
  struct stat * buf = (stat *) malloc(sizeof(stat));
  int retval;
  mode_t new_mode;
  mode_t to_add;

  if (argc != 2) exit(1);
  retval = stat(argv[1],buf);
  if (retval != 0) exit(1);

  new_mode = buf->st_mode;
/* NOTE: This gives the group >= permisions, change to suit */
  if (buf->st_mode & S_IRUSR) new_mode &= S_IRGRP;
  if (buf->st_mode & S_IWUSR) new_mode &= S_IWGRP;
  if (buf->st_mode & S_IXUSR) new_mode &= S_IXGRP;
  chmod(argv[1],new_mode);
  exit(0);
}

Using scripts:

#!/bin/sh
ls -l | fgrep $* | cut -c 2-4 | tr -d '-' | xargs --replace chmod g={} $*

find . -name \* -exec script.sh {} \;

Open invitation for any perl monk...

Corrin


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