HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. |  |
NAME |LIBRARY |SYNOPSIS |DESCRIPTION |RETURN VALUE |ERRORS |STANDARDS |HISTORY |BUGS |EXAMPLES |SEE ALSO |COLOPHON | |
listxattr(2) System Calls Manuallistxattr(2)listxattr, llistxattr, flistxattr - list extended attribute names
Standard C library (libc,-lc)
#include <sys/xattr.h>ssize_t listxattr(const char *path, char *_Nullablelist, size_tsize);ssize_t llistxattr(const char *path, char *_Nullablelist, size_tsize);ssize_t flistxattr(intfd, char *_Nullablelist, size_tsize);
Extended attributes arename:value pairs associated with inodes (files, directories, symbolic links, etc.). They are extensions to the normal attributes which are associated with all inodes in the system (i.e., thestat(2) data). A complete overview of extended attributes concepts can be found inxattr(7).listxattr() retrieves the list of extended attribute names associated with the givenpath in the filesystem. The retrieved list is placed inlist, a caller-allocated buffer whose size (in bytes) is specified in the argumentsize. The list is the set of (null-terminated) names, one after the other. Names of extended attributes to which the calling process does not have access may be omitted from the list. The length of the attribute namelist is returned.llistxattr() is identical tolistxattr(), except in the case of a symbolic link, where the list of names of extended attributes associated with the link itself is retrieved, not the file that it refers to.flistxattr() is identical tolistxattr(), only the open file referred to byfd (as returned byopen(2)) is interrogated in place ofpath. A single extended attributename is a null-terminated string. The name includes a namespace prefix; there may be several, disjoint namespaces associated with an individual inode. Ifsize is specified as zero, these calls return the current size of the list of extended attribute names (and leavelist unchanged). This can be used to determine the size of the buffer that should be supplied in a subsequent call. (But, bear in mind that there is a possibility that the set of extended attributes may change between the two calls, so that it is still necessary to check the return status from the second call.)Example Thelist of names is returned as an unordered array of null- terminated character strings (attribute names are separated by null bytes ('\0')), like this: user.name1\0system.name1\0user.name2\0 Filesystems that implement POSIX ACLs using extended attributes might return alist like this: system.posix_acl_access\0system.posix_acl_default\0On success, a nonnegative number is returned indicating the size of the extended attribute name list. On failure, -1 is returned anderrno is set to indicate the error.
E2BIGThe size of the list of extended attribute names is larger than the maximum size allowed; the list cannot be retrieved. This can happen on filesystems that support an unlimited number of extended attributes per file such as XFS, for example. See BUGS.ENOTSUP Extended attributes are not supported by the filesystem, or are disabled.ERANGEThesize of thelist buffer is too small to hold the result. In addition, the errors documented instat(2) can also occur.
Linux.
Linux 2.4, glibc 2.3.
As noted inxattr(7), the VFS imposes a limit of 64 kB on the size of the extended attribute name list returned bylistxattr(). If the total size of attribute names attached to a file exceeds this limit, it is no longer possible to retrieve the list of attribute names.
The following program demonstrates the usage oflistxattr() andgetxattr(2). For the file whose pathname is provided as a command-line argument, it lists all extended file attributes and their values. To keep the code simple, the program assumes that attribute keys and values are constant during the execution of the program. A production program should expect and handle changes during execution of the program. For example, the number of bytes required for attribute keys might increase between the two calls tolistxattr(). An application could handle this possibility using a loop that retries the call (perhaps up to a predetermined maximum number of attempts) with a larger buffer each time it fails with the errorERANGE. Calls togetxattr(2) could be handled similarly. The following output was recorded by first creating a file, setting some extended file attributes, and then listing the attributes with the example program.Example output $touch /tmp/foo; $setfattr -n user.fred -v chocolate /tmp/foo; $setfattr -n user.frieda -v bar /tmp/foo; $setfattr -n user.empty /tmp/foo; $./listxattr /tmp/foo; user.fred: chocolate user.frieda: bar user.empty: <no value>Program source (listxattr.c) #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/xattr.h> int main(int argc, char *argv[]) { char *buf, *key, *val; ssize_t buflen, keylen, vallen; if (argc != 2) { fprintf(stderr, "Usage: %s path\n", argv[0]); exit(EXIT_FAILURE); } /* * Determine the length of the buffer needed. */ buflen = listxattr(argv[1], NULL, 0); if (buflen == -1) { perror("listxattr"); exit(EXIT_FAILURE); } if (buflen == 0) { printf("%s has no attributes.\n", argv[1]); exit(EXIT_SUCCESS); } /* * Allocate the buffer. */ buf = malloc(buflen); if (buf == NULL) { perror("malloc"); exit(EXIT_FAILURE); } /* * Copy the list of attribute keys to the buffer. */ buflen = listxattr(argv[1], buf, buflen); if (buflen == -1) { perror("listxattr"); exit(EXIT_FAILURE); } /* * Loop over the list of zero terminated strings with the * attribute keys. Use the remaining buffer length to determine * the end of the list. */ key = buf; while (buflen > 0) { /* * Output attribute key. */ printf("%s: ", key); /* * Determine length of the value. */ vallen = getxattr(argv[1], key, NULL, 0); if (vallen == -1) perror("getxattr"); if (vallen > 0) { /* * Allocate value buffer. * One extra byte is needed to append 0x00. */ val = malloc(vallen + 1); if (val == NULL) { perror("malloc"); exit(EXIT_FAILURE); } /* * Copy value to buffer. */ vallen = getxattr(argv[1], key, val, vallen); if (vallen == -1) { perror("getxattr"); } else { /* * Output attribute value. */ val[vallen] = 0; printf("%s", val); } free(val); } else if (vallen == 0) { printf("<no value>"); } printf("\n"); /* * Forward to next attribute key. */ keylen = strlen(key) + 1; buflen -= keylen; key += keylen; } free(buf); exit(EXIT_SUCCESS); }getfattr(1),setfattr(1),getxattr(2),open(2),removexattr(2),setxattr(2),stat(2),symlink(7),xattr(7)
This page is part of theman-pages (Linux kernel and C library user-space interface documentation) project. Information about the project can be found at ⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report for this manual page, see ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩. This page was obtained from the tarball man-pages-6.15.tar.gz fetched from ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on 2025-08-11. If you discover any rendering problems in this HTML version of the page, or you believe there is a better or more up- to-date source for the page, or you have corrections or improvements to the information in this COLOPHON (which isnot part of the original manual page), send a mail to man-pages@man7.orgLinux man-pages 6.15 2025-05-17listxattr(2)Pages that refer to this page:getxattr(2), removexattr(2), setxattr(2), syscalls(2), symlink(7), xattr(7)
HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |