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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:
93 The maximum file link count.
95 The maximum number of bytes in terminal canonical input line.
97 The minimum maximum number of bytes for which space is available in
98 a terminal input queue.
100 The maximum number of bytes in a file name.
102 The maximum number of bytes in a pathname.
104 The maximum number of bytes which will be written atomically to a pipe.
105 .It Li _PC_CHOWN_RESTRICTED
106 Return 1 if appropriate privilege is required for the
108 system call, otherwise 0.
110 requires appropriate privilege in all cases, but this behavior was optional
111 in prior editions of the standard.
113 Return greater than zero if attempts to use pathname components longer than
117 error; otherwise, such components will be truncated to
120 requires the error in all cases, but this behavior was optional in prior
121 editions of the standard, and some
122 .No non- Ns Tn POSIX Ns -compliant
123 file systems do not support this behavior.
125 Returns the terminal character disabling value.
127 Return 1 if asynchronous I/O is supported, otherwise 0.
129 Returns 1 if prioritised I/O is supported for this file,
132 Returns 1 if synchronised I/O is supported for this file, otherwise 0.
133 .It Li _PC_ALLOC_SIZE_MIN
134 Minimum number of bytes of storage allocated for any portion of a file.
135 .It Li _PC_FILESIZEBITS
136 Number of bits needed to represent the maximum file size.
137 .It Li _PC_REC_INCR_XFER_SIZE
138 Recommended increment for file transfer sizes between
139 .Dv _PC_REC_MIN_XFER_SIZE
141 .Dv _PC_REC_MAX_XFER_SIZE .
142 .It Li _PC_REC_MAX_XFER_SIZE
143 Maximum recommended file transfer size.
144 .It Li _PC_REC_MIN_XFER_SIZE
145 Minimum recommended file transfer size.
146 .It Li _PC_REC_XFER_ALIGN
147 Recommended file transfer buffer alignment.
148 .It Li _PC_SYMLINK_MAX
149 Maximum number of bytes in a symbolic link.
150 .It Li _PC_ACL_EXTENDED
151 Returns 1 if an Access Control List (ACL) can be set on the specified
154 Returns 1 if an NFSv4 ACLs can be set on the specified
156 .It Li _PC_ACL_PATH_MAX
157 Maximum number of ACL entries per file.
158 .It Li _PC_CAP_PRESENT
159 Returns 1 if a capability state can be set on the specified file,
161 .It Li _PC_INF_PRESENT
162 Returns 1 if an information label can be set on the specified file,
164 .It Li _PC_MAC_PRESENT
165 Returns 1 if a Mandatory Access Control (MAC) label can be set on the
166 specified file, otherwise 0.
167 .It Li _PC_MIN_HOLE_SIZE
168 If a file system supports the reporting of holes (see
173 return a positive number that represents the minimum hole size returned in
175 The offsets of holes returned will be aligned to this same value.
176 A special value of 1 is returned if the file system does not specify the minimum
177 hole size but still reports holes.
184 is not successful, \-1 is returned and
186 is set appropriately.
187 Otherwise, if the variable is associated with functionality that does
188 not have a limit in the system, \-1 is returned and
191 Otherwise, the current variable value is returned.
193 If any of the following conditions occur, the
197 system calls shall return -1 and set
199 to the corresponding value.
206 The implementation does not support an association of the variable
207 name with the associated file.
216 A component of the path prefix is not a directory.
217 .It Bq Er ENAMETOOLONG
218 A component of a pathname exceeded
223 or an entire path name exceeded
227 The named file does not exist.
229 Search permission is denied for a component of the path prefix.
231 Too many symbolic links were encountered in translating the pathname.
233 An I/O error occurred while reading from or writing to the file system.
245 is not a valid open file descriptor.
247 An I/O error occurred while reading from or writing to the file system.
257 system calls first appeared in
261 system call first appeared in