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28 .\" @(#)pathconf.2 8.1 (Berkeley) 6/4/93
37 .Nd get configurable pathname variables
43 .Fn pathconf "const char *path" "int name"
45 .Fn lpathconf "const char *path" "int name"
47 .Fn fpathconf "int fd" "int name"
54 system calls provide a method for applications to determine the current
55 value of a configurable system limit or option variable associated
56 with a pathname or file descriptor.
64 argument is the name of a file or directory.
69 argument is an open file descriptor.
72 argument specifies the system variable to be queried.
73 Symbolic constants for each name value are found in the include file
80 except in the case where the named file is a symbolic link,
83 returns information about the link,
86 returns information about the file the link references.
88 The available values are as follows:
91 The maximum file link count.
93 The maximum number of bytes in terminal canonical input line.
95 The minimum maximum number of bytes for which space is available in
96 a terminal input queue.
98 The maximum number of bytes in a file name.
100 The maximum number of bytes in a pathname.
102 The maximum number of bytes which will be written atomically to a pipe.
103 .It Li _PC_CHOWN_RESTRICTED
104 Return 1 if appropriate privilege is required for the
106 system call, otherwise 0.
108 requires appropriate privilege in all cases, but this behavior was optional
109 in prior editions of the standard.
111 Return greater than zero if attempts to use pathname components longer than
115 error; otherwise, such components will be truncated to
118 requires the error in all cases, but this behavior was optional in prior
119 editions of the standard, and some
120 .No non- Ns Tn POSIX Ns -compliant
121 file systems do not support this behavior.
123 Returns the terminal character disabling value.
125 Return 1 if asynchronous I/O is supported, otherwise 0.
127 Returns 1 if prioritised I/O is supported for this file,
130 Returns 1 if synchronised I/O is supported for this file, otherwise 0.
131 .It Li _PC_ALLOC_SIZE_MIN
132 Minimum number of bytes of storage allocated for any portion of a file.
133 .It Li _PC_FILESIZEBITS
134 Number of bits needed to represent the maximum file size.
135 .It Li _PC_REC_INCR_XFER_SIZE
136 Recommended increment for file transfer sizes between
137 .Dv _PC_REC_MIN_XFER_SIZE
139 .Dv _PC_REC_MAX_XFER_SIZE .
140 .It Li _PC_REC_MAX_XFER_SIZE
141 Maximum recommended file transfer size.
142 .It Li _PC_REC_MIN_XFER_SIZE
143 Minimum recommended file transfer size.
144 .It Li _PC_REC_XFER_ALIGN
145 Recommended file transfer buffer alignment.
146 .It Li _PC_SYMLINK_MAX
147 Maximum number of bytes in a symbolic link.
148 .It Li _PC_ACL_EXTENDED
149 Returns 1 if an Access Control List (ACL) can be set on the specified
152 Returns 1 if an NFSv4 ACLs can be set on the specified
154 .It Li _PC_ACL_PATH_MAX
155 Maximum number of ACL entries per file.
156 .It Li _PC_CAP_PRESENT
157 Returns 1 if a capability state can be set on the specified file,
159 .It Li _PC_INF_PRESENT
160 Returns 1 if an information label can be set on the specified file,
162 .It Li _PC_MAC_PRESENT
163 Returns 1 if a Mandatory Access Control (MAC) label can be set on the
164 specified file, otherwise 0.
165 .It Li _PC_MIN_HOLE_SIZE
166 If a file system supports the reporting of holes (see
171 return a positive number that represents the minimum hole size returned in
173 The offsets of holes returned will be aligned to this same value.
174 A special value of 1 is returned if the file system does not specify the minimum
175 hole size but still reports holes.
176 .It Li _PC_DEALLOC_PRESENT
177 Return 1 if a file system supports hole-punching (see
186 is not successful, \-1 is returned and
188 is set appropriately.
189 Otherwise, if the variable is associated with functionality that does
190 not have a limit in the system, \-1 is returned and
193 Otherwise, the current variable value is returned.
195 If any of the following conditions occur, the
199 system calls shall return -1 and set
201 to the corresponding value.
208 The implementation does not support an association of the variable
209 name with the associated file.
218 A component of the path prefix is not a directory.
219 .It Bq Er ENAMETOOLONG
220 A component of a pathname exceeded
225 or an entire path name exceeded
229 The named file does not exist.
231 Search permission is denied for a component of the path prefix.
233 Too many symbolic links were encountered in translating the pathname.
235 An I/O error occurred while reading from or writing to the file system.
237 Corrupted data was detected while reading from the file system.
249 is not a valid open file descriptor.
251 An I/O error occurred while reading from or writing to the file system.
253 Corrupted data was detected while reading from the file system.
263 system calls first appeared in
267 system call first appeared in