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28 .\" @(#)pathconf.2 8.1 (Berkeley) 6/4/93
38 .Nd get configurable pathname variables
44 .Fn pathconf "const char *path" "int name"
46 .Fn lpathconf "const char *path" "int name"
48 .Fn fpathconf "int fd" "int name"
55 system calls provide a method for applications to determine the current
56 value of a configurable system limit or option variable associated
57 with a pathname or file descriptor.
65 argument is the name of a file or directory.
70 argument is an open file descriptor.
73 argument specifies the system variable to be queried.
74 Symbolic constants for each name value are found in the include file
81 except in the case where the named file is a symbolic link,
84 returns information about the link,
87 returns information about the file the link references.
89 The available values are as follows:
94 The maximum file link count.
96 The maximum number of bytes in terminal canonical input line.
98 The minimum maximum number of bytes for which space is available in
99 a terminal input queue.
101 The maximum number of bytes in a file name.
103 The maximum number of bytes in a pathname.
105 The maximum number of bytes which will be written atomically to a pipe.
106 .It Li _PC_CHOWN_RESTRICTED
107 Return 1 if appropriate privilege is required for the
109 system call, otherwise 0.
111 requires appropriate privilege in all cases, but this behavior was optional
112 in prior editions of the standard.
114 Return greater than zero if attempts to use pathname components longer than
118 error; otherwise, such components will be truncated to
121 requires the error in all cases, but this behavior was optional in prior
122 editions of the standard, and some
123 .No non- Ns Tn POSIX Ns -compliant
124 file systems do not support this behavior.
126 Returns the terminal character disabling value.
128 Return 1 if asynchronous I/O is supported, otherwise 0.
130 Returns 1 if prioritised I/O is supported for this file,
133 Returns 1 if synchronised I/O is supported for this file, otherwise 0.
134 .It Li _PC_ALLOC_SIZE_MIN
135 Minimum number of bytes of storage allocated for any portion of a file.
136 .It Li _PC_FILESIZEBITS
137 Number of bits needed to represent the maximum file size.
138 .It Li _PC_REC_INCR_XFER_SIZE
139 Recommended increment for file transfer sizes between
140 .Dv _PC_REC_MIN_XFER_SIZE
142 .Dv _PC_REC_MAX_XFER_SIZE .
143 .It Li _PC_REC_MAX_XFER_SIZE
144 Maximum recommended file transfer size.
145 .It Li _PC_REC_MIN_XFER_SIZE
146 Minimum recommended file transfer size.
147 .It Li _PC_REC_XFER_ALIGN
148 Recommended file transfer buffer alignment.
149 .It Li _PC_SYMLINK_MAX
150 Maximum number of bytes in a symbolic link.
151 .It Li _PC_ACL_EXTENDED
152 Returns 1 if an Access Control List (ACL) can be set on the specified
155 Returns 1 if an NFSv4 ACLs can be set on the specified
157 .It Li _PC_ACL_PATH_MAX
158 Maximum number of ACL entries per file.
159 .It Li _PC_CAP_PRESENT
160 Returns 1 if a capability state can be set on the specified file,
162 .It Li _PC_INF_PRESENT
163 Returns 1 if an information label can be set on the specified file,
165 .It Li _PC_MAC_PRESENT
166 Returns 1 if a Mandatory Access Control (MAC) label can be set on the
167 specified file, otherwise 0.
168 .It Li _PC_MIN_HOLE_SIZE
169 If a file system supports the reporting of holes (see
174 return a positive number that represents the minimum hole size returned in
176 The offsets of holes returned will be aligned to this same value.
177 A special value of 1 is returned if the file system does not specify the minimum
178 hole size but still reports holes.
185 is not successful, \-1 is returned and
187 is set appropriately.
188 Otherwise, if the variable is associated with functionality that does
189 not have a limit in the system, \-1 is returned and
192 Otherwise, the current variable value is returned.
194 If any of the following conditions occur, the
198 system calls shall return -1 and set
200 to the corresponding value.
207 The implementation does not support an association of the variable
208 name with the associated file.
217 A component of the path prefix is not a directory.
218 .It Bq Er ENAMETOOLONG
219 A component of a pathname exceeded
224 or an entire path name exceeded
228 The named file does not exist.
230 Search permission is denied for a component of the path prefix.
232 Too many symbolic links were encountered in translating the pathname.
234 An I/O error occurred while reading from or writing to the file system.
246 is not a valid open file descriptor.
248 An I/O error occurred while reading from or writing to the file system.
258 system calls first appeared in
262 system call first appeared in