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32 .\" @(#)pathconf.2 8.1 (Berkeley) 6/4/93
41 .Nd get configurable pathname variables
47 .Fn pathconf "const char *path" "int name"
49 .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.
63 argument is the name of a file or directory.
68 argument is an open file descriptor.
71 argument specifies the system variable to be queried.
72 Symbolic constants for each name value are found in the include file
75 The available values are as follows:
80 The maximum file link count.
82 The maximum number of bytes in terminal canonical input line.
84 The minimum maximum number of bytes for which space is available in
85 a terminal input queue.
87 The maximum number of bytes in a file name.
89 The maximum number of bytes in a pathname.
91 The maximum number of bytes which will be written atomically to a pipe.
92 .It Li _PC_CHOWN_RESTRICTED
93 Return 1 if appropriate privilege is required for the
95 system call, otherwise 0.
97 requires appropriate privilege in all cases, but this behavior was optional
98 in prior editions of the standard.
100 Return greater than zero if attempts to use pathname components longer than
104 error; otherwise, such components will be truncated to
107 requires the error in all cases, but this behavior was optional in prior
108 editions of the standard, and some
109 .No non- Ns Tn POSIX Ns -compliant
110 file systems do not support this behavior.
112 Returns the terminal character disabling value.
114 Return 1 if asynchronous I/O is supported, otherwise 0.
116 Returns 1 if prioritised I/O is supported for this file,
119 Returns 1 if synchronised I/O is supported for this file, otherwise 0.
120 .It Li _PC_ALLOC_SIZE_MIN
121 Minimum number of bytes of storage allocated for any portion of a file.
122 .It Li _PC_FILESIZEBITS
123 Number of bits needed to represent the maximum file size.
124 .It Li _PC_REC_INCR_XFER_SIZE
125 Recommended increment for file transfer sizes between
126 .Dv _PC_REC_MIN_XFER_SIZE
128 .Dv _PC_REC_MAX_XFER_SIZE .
129 .It Li _PC_REC_MAX_XFER_SIZE
130 Maximum recommended file transfer size.
131 .It Li _PC_REC_MIN_XFER_SIZE
132 Minimum recommended file transfer size.
133 .It Li _PC_REC_XFER_ALIGN
134 Recommended file transfer buffer alignment.
135 .It Li _PC_SYMLINK_MAX
136 Maximum number of bytes in a symbolic link.
137 .It Li _PC_ACL_EXTENDED
138 Returns 1 if an Access Control List (ACL) can be set on the specified
140 .It Li _PC_ACL_PATH_MAX
141 Maximum number of ACL entries per file.
142 .It Li _PC_CAP_PRESENT
143 Returns 1 if a capability state can be set on the specified file,
145 .It Li _PC_INF_PRESENT
146 Returns 1 if an information label can be set on the specified file,
148 .It Li _PC_MAC_PRESENT
149 Returns 1 if a Mandatory Access Control (MAC) label can be set on the
150 specified file, otherwise 0.
157 is not successful, \-1 is returned and
159 is set appropriately.
160 Otherwise, if the variable is associated with functionality that does
161 not have a limit in the system, \-1 is returned and
164 Otherwise, the current variable value is returned.
166 If any of the following conditions occur, the
170 system calls shall return -1 and set
172 to the corresponding value.
179 The implementation does not support an association of the variable
180 name with the associated file.
189 A component of the path prefix is not a directory.
190 .It Bq Er ENAMETOOLONG
191 A component of a pathname exceeded
196 or an entire path name exceeded
200 The named file does not exist.
202 Search permission is denied for a component of the path prefix.
204 Too many symbolic links were encountered in translating the pathname.
206 An I/O error occurred while reading from or writing to the file system.
218 is not a valid open file descriptor.
220 An I/O error occurred while reading from or writing to the file system.
229 system calls first appeared in