files/t_chown.c

This is files/t_chown.c (Listing 15-2, page 293), an example from the book, The Linux Programming Interface.

The source code file is copyright 2024, Michael Kerrisk, and is licensed under the GNU General Public License, version 3.

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#include <pwd.h>
#include <grp.h>
#include "ugid_functions.h"             /* Declarations of userIdFromName()
                                           and groupIdFromName() */
#include "tlpi_hdr.h"
int
main(int argc, char *argv[])
{
    uid_t uid;
    gid_t gid;
    int j;
    Boolean errFnd;

    if (argc < 3 || strcmp(argv[1], "--help") == 0)
        usageErr("%s owner group [file...]\n"
                "        owner or group can be '-', "
                "meaning leave unchanged\n", argv[0]);

    if (strcmp(argv[1], "-") == 0) {            /* "-" ==> don't change owner */
        uid = -1;
    } else {                                    /* Turn user name into UID */
        uid = userIdFromName(argv[1]);
        if (uid == -1)
            fatal("No such user (%s)", argv[1]);
    }

    if (strcmp(argv[2], "-") == 0) {            /* "-" ==> don't change group */
        gid = -1;
    } else {                                    /* Turn group name into GID */
        gid = groupIdFromName(argv[2]);
        if (gid == -1)
            fatal("No such group (%s)", argv[2]);
    }

    /* Change ownership of all files named in remaining arguments */

    errFnd = FALSE;
    for (j = 3; j < argc; j++) {
        if (chown(argv[j], uid, gid) == -1) {
            errMsg("chown: %s", argv[j]);
            errFnd = TRUE;
        }
    }

    exit(errFnd ? EXIT_FAILURE : EXIT_SUCCESS);
}

 

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