--- name: "pathconf" section: "3" platform: "linux" package: "man-pages" version: "6.19-1" release: "Arch Linux 2026-11-01" platforms: ["linux"] url: "https://new.carta.tech/fpathconf/3" --- # pathconf(3) get configuration values for files Part of [fpathconf(3)](/fpathconf/3.md). ## NAME fpathconf, pathconf - get configuration values for files ## LIBRARY Standard C library (*libc*, *-lc*) ## SYNOPSIS ``` #include ``` **long fpathconf(int** *fd***, int** *name***);** **long pathconf(const char \****path***, int** *name***);** ## DESCRIPTION **fpathconf**() gets a value for the configuration option *name* for the open file descriptor *fd*. **pathconf**() gets a value for configuration option *name* for the filename *path*. The corresponding macros defined in *\* are minimum values; if an application wants to take advantage of values which may change, a call to **fpathconf**() or **pathconf**() can be made, which may yield more liberal results. Setting *name* equal to one of the following constants returns the following configuration options: - **\_PC\_LINK\_MAX** The maximum number of links to the file. If *fd* or *path* refer to a directory, then the value applies to the whole directory. The corresponding macro is **\_POSIX\_LINK\_MAX**. - **\_PC\_MAX\_CANON** The maximum length of a formatted input line, where *fd* or *path* must refer to a terminal. The corresponding macro is **\_POSIX\_MAX\_CANON**. - **\_PC\_MAX\_INPUT** The maximum length of an input line, where *fd* or *path* must refer to a terminal. The corresponding macro is **\_POSIX\_MAX\_INPUT**. - **\_PC\_NAME\_MAX** The maximum length of a filename in the directory *path* or *fd* that the process is allowed to create. The corresponding macro is **\_POSIX\_NAME\_MAX**. - **\_PC\_PATH\_MAX** The maximum length of a relative pathname when *path* or *fd* is the current working directory. The corresponding macro is **\_POSIX\_PATH\_MAX**. - **\_PC\_PIPE\_BUF** The maximum number of bytes that can be written atomically to a pipe of FIFO. For **fpathconf**(), *fd* should refer to a pipe or FIFO. For **fpathconf**(), *path* should refer to a FIFO or a directory; in the latter case, the returned value corresponds to FIFOs created in that directory. The corresponding macro is **\_POSIX\_PIPE\_BUF**. - **\_PC\_CHOWN\_RESTRICTED** This returns a positive value if the use of [**chown**(2)](/chown/2.md) and [**fchown**(2)](/fchown/2.md) for changing a file's user ID is restricted to a process with appropriate privileges, and changing a file's group ID to a value other than the process's effective group ID or one of its supplementary group IDs is restricted to a process with appropriate privileges. According to POSIX.1, this variable shall always be defined with a value other than -1. The corresponding macro is **\_POSIX\_CHOWN\_RESTRICTED**. - If *fd* or *path* refers to a directory, then the return value applies to all files in that directory. - **\_PC\_NO\_TRUNC** This returns nonzero if accessing filenames longer than **\_POSIX\_NAME\_MAX** generates an error. The corresponding macro is **\_POSIX\_NO\_TRUNC**. - **\_PC\_VDISABLE** This returns nonzero if special character processing can be disabled, where *fd* or *path* must refer to a terminal. ## RETURN VALUE The return value of these functions is one of the following: - • On error, -1 is returned and *errno* is set to indicate the error (for example, **EINVAL**, indicating that *name* is invalid). - • If *name* corresponds to a maximum or minimum limit, and that limit is indeterminate, -1 is returned and *errno* is not changed. (To distinguish an indeterminate limit from an error, set *errno* to zero before the call, and then check whether *errno* is nonzero when -1 is returned.) - • If *name* corresponds to an option, a positive value is returned if the option is supported, and -1 is returned if the option is not supported. - • Otherwise, the current value of the option or limit is returned. This value will not be more restrictive than the corresponding value that was described to the application in *\* or *\* when the application was compiled. ## ERRORS - **EACCES** (**pathconf**()) Search permission is denied for one of the directories in the path prefix of *path*. - **EBADF** (**fpathconf**()) *fd* is not a valid file descriptor. - **EINVAL** *name* is invalid. - **EINVAL** The implementation does not support an association of *name* with the specified file. - **ELOOP** (**pathconf**()) Too many symbolic links were encountered while resolving *path*. - **ENAMETOOLONG** (**pathconf**()) *path* is too long. - **ENOENT** (**pathconf**()) A component of *path* does not exist, or *path* is an empty string. - **ENOTDIR** (**pathconf**()) A component used as a directory in *path* is not in fact a directory. ## ATTRIBUTES For an explanation of the terms used in this section, see [**attributes**(7)](/attributes/7.md). | | | | | --- | --- | --- | | **Interface** | **Attribute** | **Value** | | **fpathconf**(), **pathconf**() | Thread safety | MT-Safe | ## STANDARDS POSIX.1-2008. ## HISTORY POSIX.1-2001. ## NOTES Files with name lengths longer than the value returned for *name* equal to **\_PC\_NAME\_MAX** may exist in the given directory. Some returned values may be huge; they are not suitable for allocating memory. ## SEE ALSO [**getconf**(1)](/getconf/1.md), [**open**(2)](/open/2.md), [**statfs**(2)](/statfs/2.md), [**confstr**(3)](/confstr/3.md), [**sysconf**(3)](/sysconf/3.md)