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> closedir(3)
> fnmatch(3)
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man page of alphasort

alphasort: scan a directory for matching entries


scandir, alphasort, versionsort - scan a directory for matching entries


#include <dirent.h> int scandir(const char *dirp, struct dirent ***namelist, int (*filter)(const struct dirent *), int (*compar)(const struct dirent **, const struct dirent **)); int alphasort(const void *a, const void *b); int versionsort(const void *a, const void *b); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): scandir(), alphasort(): _BSD_SOURCE || _SVID_SOURCE versionsort(): _GNU_SOURCE


The scandir() function scans the directory dirp, calling filter() on each directory entry. Entries for which filter() returns nonzero are stored in strings allocated via malloc(3), sorted using qsort(3) with the comparison function compar(), and collected in array namelist which is allocated via malloc(3). If filter is NULL, all entries are selected. The alphasort() and versionsort() functions can be used as the comparison function compar(). The former sorts directory entries using strcoll(3), the latter using strverscmp(3) on the strings (*a)->d_name and (*b)->d_name.


The scandir() function returns the number of directory entries selected or -1 if an error occurs. The alphasort() and versionsort() functions return an integer less than, equal to, or greater than zero if the first argument is considered to be respectively less than, equal to, or greater than the second.
ENOMEM Insufficient memory to complete the operation.
versionsort() was added to glibc in version 2.1.


alphasort() and scandir() are specified in POSIX.1-2008, and are widely available. versionsort() is a GNU extension. The functions scandir() and alphasort() are from 4.3BSD, and have been available under Linux since libc4. Libc4 and libc5 use the more precise prototype int alphasort(const struct dirent ** a, const struct dirent **b); but glibc 2.0 returns to the imprecise BSD prototype. The function versionsort() is a GNU extension, available since glibc 2.1. Since glibc 2.1, alphasort() calls strcoll(3); earlier it used strcmp(3).


#define _SVID_SOURCE /* print files in current directory in reverse order */ #include <dirent.h> int main(void) { struct dirent **namelist; int n; n = scandir(".", &namelist, 0, alphasort); if (n < 0) perror("scandir"); else { while (n--) { printf("%s\n", namelist[n]->d_name); free(namelist[n]); } free(namelist); } }


closedir(3), fnmatch(3), opendir(3), readdir(3), rewinddir(3), seekdir(3), strcmp(3), strcoll(3), strverscmp(3), telldir(3)


This page is part of release 3.27 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at //www.kernel.org/doc/man-pages/. ALPHASORT(3)

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