NAME
dirname, basename - 分析路径成员
总览 (SYNOPSIS)
#include <libgen.h> char *dirname(char *path); char *basename(char *path);
描述 (DESCRIPTION)
dirname 和 basename 把 以 null 结尾 的 路径名 分解为 目录 和 文件名. 一般情况下, dirname 返回 路径名 的 前面部分, 直到 (但不包括) ***一个 '/', 而 basename 则 返回 ***一个 '/' 后面 的 内容. 如果 路径名 以 '/' 结尾, 该 '/' 被认为 不是 路径名 的 一部分.
如果 路径名 path 不包含 斜杠 '/', dirname 返回 字符串 ".", 而 basename 返回 path 的 副本. 如果 路径名 path 是 "/", 则 dirname 和 basename 均 返回 "/". 如果 路径名 path 是 NULL 指针 或 指向 空串, 则 dirname 和 basename 均 返回 ".".
把 dirname 返回的 字符串, "/", 和 basename 返回的 字符串 连接 起来, 能够 产生 一个 完整 的 路径名.
无论 dirname 还是 basename 都 有可能 更改 path 的 内容, 因此 如果 需要 保护 原有 路径名, 应该 传送 副本 作为 参数. 此外, dirname 和 basename 返回的 指针 可能 指向 一块 静态分配 的 内存, 会被 下次 调用 覆盖.
下面 的 例子 (摘自 SUSv2) 展示了 对于 不同的 路径名, dirname 和 basename 返回 的 字符串:
path dirname basename "/usr/lib" "/usr" "lib" "/usr/" "/" "usr" "usr" "." "usr" "/" "/" "/" "." "." "." ".." "." ".."
示例 (EXAMPLE)
char *dirc, *basec, *bname, *dname;
char *path = "/etc/passwd";
dirc = strdup(path);
basec = strdup(path);
dname = dirname(dirc);
bname = basename(basec);
printf("dirname=%s, basename=%s\n", dname, bname);
free(dirc);
free(basec);
返回值 (RETURN VALUE)
dirname 和 basename 均 返回 以 null 结尾的 字符串 的 指针.
BUGS
在 glibc 的 各个 版本 中, 直到 (并包括) 2.2.1, dirname 无法 正确 处理 以 '/' 字符 结尾 的 路径名. 如果 参数 是 NULL 指针, 他 还会 产生 段冲突 (segmentation violation).
遵循 (CONFORMING TO)
SUSv2
另见 (SEE ALSO)
dirname(1), basename(1)
#p#
NAME
dirname, basename - Parse pathname components
SYNOPSIS
#include <libgen.h> char *dirname(char *path); char *basename(char *path);
DESCRIPTION
Warning: there are two different functions basename - see below.
The functions dirname and basename break a null-terminated pathname string into directory and filename components. In the usual case, dirname returns the string up to, but not including, the final '/', and basename returns the component following the final '/'. Trailing '/' characters are not counted as part of the pathname.
If path does not contain a slash, dirname returns the string "." while basename returns a copy of path. If path is the string "/", then both dirname and basename return the string "/". If path is a NULL pointer or points to an empty string, then both dirname and basename return the string ".".
Concatenating the string returned by dirname, a "/", and the string returned by basename yields a complete pathname.
Both dirname and basename may modify the contents of path, so copies should be passed to these functions. Furthermore, dirname and basename may return pointers to statically allocated memory which may be overwritten by subsequent calls.
The following list of examples (taken from SUSv2) shows the strings returned by dirname and basename for different paths:
path dirname basename "/usr/lib" "/usr" "lib" "/usr/" "/" "usr" "usr" "." "usr" "/" "/" "/" "." "." "." ".." "." ".."
EXAMPLE
-
char *dirc, *basec, *bname, *dname; char *path = "/etc/passwd"; dirc = strdup(path); basec = strdup(path); dname = dirname(dirc); bname = basename(basec); printf("dirname=%s, basename=%s\n", dname, bname);
RETURN VALUE
Both dirname and basename return pointers to null-terminated strings.
NOTES
There are two different versions of basename - the POSIX version described above, and the GNU version one gets after
#define _GNU_SOURCE
#include <string.h>
The GNU version never modifies its argument, and returns the empty string when path has a trailing slash, and in particular also when it is "/". There is no GNU version of dirname.
With glibc, one gets the POSIX version of basename when <libgen.h> is included, and the GNU version otherwise.
BUGS
In the glibc implementation of the POSIX versions of these functions they modify their argument, and segfault when called with a static string like "/usr/". Before glibc 2.2.1, the glibc version of dirname did not correctly handle pathnames with trailing '/' characters, and generated a segfault if given a NULL argument.
CONFORMING TO
POSIX 1003.1-2001
SEE ALSO
dirname(1), basename(1),
