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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 fpathconf "int fd" "int name"
51 system calls provide a method for applications to determine the current
52 value of a configurable system limit or option variable associated
53 with a pathname or file descriptor.
59 argument is the name of a file or directory.
64 argument is an open file descriptor.
67 argument specifies the system variable to be queried.
68 Symbolic constants for each name value are found in the include file
71 The available values are as follows:
76 The maximum file link count.
78 The maximum number of bytes in terminal canonical input line.
80 The minimum maximum number of bytes for which space is available in
81 a terminal input queue.
83 The maximum number of bytes in a file name.
85 The maximum number of bytes in a pathname.
87 The maximum number of bytes which will be written atomically to a pipe.
88 .It Li _PC_CHOWN_RESTRICTED
89 Return 1 if appropriate privilege is required for the
91 system call, otherwise 0.
93 requires appropriate privilege in all cases, but this behavior was optional
94 in prior editions of the standard.
96 Return greater than zero if attempts to use pathname components longer than
100 error; otherwise, such components will be truncated to
103 requires the error in all cases, but this behavior was optional in prior
104 editions of the standard, and some
105 .No non- Ns Tn POSIX Ns -compliant
106 file systems do not support this behavior.
108 Returns the terminal character disabling value.
110 Return 1 if asynchronous I/O is supported, otherwise 0.
112 Returns 1 if prioritised I/O is supported for this file,
115 Returns 1 if synchronised I/O is supported for this file, otherwise 0.
116 .It Li _PC_ALLOC_SIZE_MIN
117 Minimum number of bytes of storage allocated for any portion of a file.
118 .It Li _PC_FILESIZEBITS
119 Number of bits needed to represent the maximum file size.
120 .It Li _PC_REC_INCR_XFER_SIZE
121 Recommended increment for file transfer sizes between
122 .Dv _PC_REC_MIN_XFER_SIZE
124 .Dv _PC_REC_MAX_XFER_SIZE .
125 .It Li _PC_REC_MAX_XFER_SIZE
126 Maximum recommended file transfer size.
127 .It Li _PC_REC_MIN_XFER_SIZE
128 Minimum recommended file transfer size.
129 .It Li _PC_REC_XFER_ALIGN
130 Recommended file transfer buffer alignment.
131 .It Li _PC_SYMLINK_MAX
132 Maximum number of bytes in a symbolic link.
133 .It Li _PC_ACL_EXTENDED
134 Returns 1 if an Access Control List (ACL) can be set on the specified
136 .It Li _PC_ACL_PATH_MAX
137 Maximum number of ACL entries per file.
138 .It Li _PC_CAP_PRESENT
139 Returns 1 if a capability state can be set on the specified file,
141 .It Li _PC_INF_PRESENT
142 Returns 1 if an information label can be set on the specified file,
144 .It Li _PC_MAC_PRESENT
145 Returns 1 if a Mandatory Access Control (MAC) label can be set on the
146 specified file, otherwise 0.
147 .It Li _PC_MIN_HOLE_SIZE
148 If a file system supports the reporting of holes (see
153 return a positive number that represents the minimum hole size returned in
155 The offsets of holes returned will be aligned to this same value.
156 A special value of 1 is returned if the file system does not specify the minimum
157 hole size but still reports holes.
164 is not successful, \-1 is returned and
166 is set appropriately.
167 Otherwise, if the variable is associated with functionality that does
168 not have a limit in the system, \-1 is returned and
171 Otherwise, the current variable value is returned.
173 If any of the following conditions occur, the
177 system calls shall return -1 and set
179 to the corresponding value.
186 The implementation does not support an association of the variable
187 name with the associated file.
196 A component of the path prefix is not a directory.
197 .It Bq Er ENAMETOOLONG
198 A component of a pathname exceeded
203 or an entire path name exceeded
207 The named file does not exist.
209 Search permission is denied for a component of the path prefix.
211 Too many symbolic links were encountered in translating the pathname.
213 An I/O error occurred while reading from or writing to the file system.
225 is not a valid open file descriptor.
227 An I/O error occurred while reading from or writing to the file system.
237 system calls first appeared in