This is xattr/xattr_view.c (Listing 16-1, page 317), an example from the book, The Linux Programming Interface.

The source code file is copyright 2022, Michael Kerrisk, and is licensed under the GNU General Public License, version 3.

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Function list (Bold in this list means a function is not static)

/* view_xattr.c

   Display the extended attributes of a file.

   This program is Linux (2.6 and later) specific.

   See also t_setxattr.c.
#include <sys/xattr.h>
#include "tlpi_hdr.h"

#define XATTR_SIZE 10000
static void
usageError(char *progName)
    fprintf(stderr, "Usage: %s [-x] file...\n", progName);
main(int argc, char *argv[])
    char list[XATTR_SIZE], value[XATTR_SIZE];
    ssize_t listLen, valueLen;
    int ns, j, k, opt;
    Boolean hexDisplay;

    hexDisplay = 0;
    while ((opt = getopt(argc, argv, "x")) != -1) {
        switch (opt) {
        case 'x': hexDisplay = 1;       break;
        case '?': usageError(argv[0]);

    if (optind >= argc)

    for (j = optind; j < argc; j++) {
        listLen = listxattr(argv[j], list, XATTR_SIZE);
        if (listLen == -1)

        printf("%s:\n", argv[j]);

        /* Loop through all EA names, displaying name + value */

        for (ns = 0; ns < listLen; ns += strlen(&list[ns]) + 1) {
            printf("        name=%s; ", &list[ns]);

            valueLen = getxattr(argv[j], &list[ns], value, XATTR_SIZE);
            if (valueLen == -1) {
                printf("couldn't get value");
            } else if (!hexDisplay) {
                printf("value=%.*s", (int) valueLen, value);
            } else {
                for (k = 0; k < valueLen; k++)
                    printf("%02x ", (unsigned char) value[k]);





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