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32 .\" @(#)truncate.2 8.1 (Berkeley) 6/4/93
41 .Nd truncate or extend a file to a specified length
43 .Fd #include <unistd.h>
45 .Fn truncate "const char *path" "off_t length"
47 .Fn ftruncate "int fd" "off_t length"
50 causes the file named by
54 to be truncated or extended to
56 bytes in size. If the file
57 was larger than this size, the extra data
59 If the file was smaller than this size,
60 it will be extended as if by writing bytes
64 the file must be open for writing.
66 A value of 0 is returned if the call succeeds. If the call
67 fails a -1 is returned, and the global variable
73 .Bl -tag -width [ENOTDIR]
75 A component of the path prefix is not a directory.
76 .It Bq Er ENAMETOOLONG
77 A component of a pathname exceeded 255 characters,
78 or an entire path name exceeded 1023 characters.
80 The named file does not exist.
82 Search permission is denied for a component of the path prefix.
84 The named file is not writable by the user.
86 Too many symbolic links were encountered in translating the pathname.
88 The named file is a directory.
90 The named file resides on a read-only file system.
92 The file is a pure procedure (shared text) file that is being executed.
94 An I/O error occurred updating the inode.
97 points outside the process's allocated address space.
102 .Bl -tag -width [ENOTDIR]
106 is not a valid descriptor.
110 references a socket, not a file.
114 is not open for writing.
119 These calls should be generalized to allow ranges
120 of bytes in a file to be discarded.
124 to extend a file is not portable.
128 function call appeared in