chmod 775 on a symbolic link (not on its target)?

[Romaric Guilloud]

How to change the mode of a symbolic link (thought first chmod -h would make it, then found out it does not since it's an option of chown, not chmod :-(
Thanks in advance.
Regards,
Romaric.

[Stefan Farrelly · Accepted solution]

You have to use the hidden lchmod() C function to change permissions on symbolic links - its the only way. Heres a C program which will allow you to do it, all you need to do is compile it;

cc -o lchmod lchmod.c

#include
#include
#include

#define assign_errno(x) ((errno != 0) ? errno : (x))

static void problem(msg,err)
char *msg;
int err;
{
(void) fprintf(stderr,"%s - (%d)\n",msg,err);
(void) fflush(stderr);
return;
} /* problem */

int main(argc,argv)
int argc;
char *argv[];
{
int cc = 0;
char s_err[512];

if (argc > 2)
{
mode_t mode = 0;
char *dummy = NULL;
int i = 2;

mode = (mode_t) strtoul(argv[1],&dummy,8);
while (i < argc && cc == 0)
{
cc = lchmod(argv[i],mode);
if (cc != 0)
{
cc = assign_errno(-1);
(void) sprintf(s_err,"%s failed. File '%s'",argv[0],argv[i]);
problem(s_err,cc);
}
++i;
}
}
else
{
cc = 255;
(void) sprintf(s_err,"Usage: %s Octal_Mode file1 [file2 ...]",
argv[0]);
problem(s_err,cc);
}
return(cc);
}

[Mark Grant]

You do not need to do this because the modes of symbolic links are ignored. However, if you really want to, to make it all look pretty for example, you can always change your umask before creating the symbolic link.

[Romaric Guilloud]

Thank you for the piece of code Stefan; indeed it's for "esthetical" reasons that I needed this change.
Regards,

[Greg White]

Hello Romaric,

There was a thread very similar to this about a month earlier. I think that you will find that the actual author of that C code is none other than A. Clay Stephenson.

Please see the attached link for other ways to handle your problem.

http://forums1.itrc.hp.com/service/forums/parseCurl.do?CURL=%2Fcm%2FQuestionAnswer%2F1%2C%2C0xffcd12980463e24797ab1fdd8ed71fe0%2C00.html&admit=716493758+1066052317656+28353475

Greg