Making a file read only

[linuxlover]

How to make a file read only using C program??

Is there a function called chmod and what is its use??

What is meant by r+ ,w+ ,a+ modes in file?

[laserlight]

Since you appear to be possibly on the right track with your reference to chmod, I suggest that you search the Web for more information.

[JohnGraham]

Is there a function called chmod and what is its use??

Yeah, POSIX provides this, but it's not portable to other OS's. Man pages can be Googled quite easily.

[linuxlover]

Yeah, POSIX provides this, but it's not portable to other OS's. Man pages can be Googled quite easily.

Any other way instead of using library functions????

[laserlight]

Any other way instead of using library functions?

What exactly do you mean by that?

[linuxlover]

What exactly do you mean by that?

ie. by using some code..

[linuxlover]

found chmod here chmod - Linux Command - Unix Command

[VirtualAce]

If you are in Windows and only Windows then I would use the Windows API. If you want portable code then use the CRT.

[laserlight]

ie. by using some code..

You write code that uses library functions. I don't see what else you are getting at here.

If you want portable code then use the CRT.

I do not think that the standard C library has support for this.

[VirtualAce]

I do not think that the standard C library has support for this.

Come to think of it I don't think it does either. See...this is why I should stay away from the C board.

[Adak]

This was part of the AT&T Unix standard, and incorporated into Turbo C. There was a more extensive alternative of this, that was for DOS only (named _chmod), and it may still work in Windows, but far safer to use the Windows API unless Microsoft has stated that they will continue to keep the old standard for this, in their OS.

chmod   Changes access mode.
 Syntax:
   int chmod(const char *path, int amode);

 Prototype in:
 io.h

 Remarks:
chmod sets the file-access permissions of the file given by path according
to the mask given by amode.

path points to a string; *path is the first character of that string.

amode can contain one or both of the symbolic constants S_IWRITE and S_IREAD
(defined in sys\stat.h).

   Value of amode   ³ Access permission
   S_IWRITE         ³ Permission to write
   S_IREAD          ³ Permission to read
   S_IREAD|S_IWRITE ³ Permission to read and write

 Return Value:
Upon successfully changing the file-access mode, chmod returns 0.

Otherwise, chmod returns a value of -1 and the global variable errno is set
to one of the following:

 Setting ³ Description
 ENOENT  ³ Path or file name not found
 EACCES  ³ Permission denied

 Portability:
chmod is available on UNIX systems.

 See Also:
  _chmod

 Example:
 #include <sys\stat.h>
 #include <stdio.h>
 #include <io.h>

 void make_read_only(char *filename);

 int main(void)
 {
    make_read_only("NOTEXIST.FIL");
    make_read_only("MYFILE.FIL");
    return 0;
 }

 void make_read_only(char *filename)
 {
    int stat;

    stat = chmod(filename, S_IREAD);
    if (stat)
       printf("Couldn't make %s read-only\n", filename);
    else
       printf("Made %s read-only\n", filename);
 }