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33 .Nd truncate or extend the length of files
56 utility adjusts the length of each regular file given on the command-line.
58 The following options are available:
59 .Bl -tag -width indent
61 Do not create files if they do not exist.
64 utility does not treat this as an error.
65 No error messages are displayed
66 and the exit value is not affected.
68 Truncate files to the length of the file
79 argument is preceded by a plus sign
81 files will be extended by this number of bytes.
84 argument is preceded by a dash
86 file lengths will be reduced by no more than this number of bytes,
87 to a minimum length of zero bytes.
90 argument specifies an absolute length to which all files
91 should be extended or reduced as appropriate.
95 argument may be suffixed with one of
100 to indicate a multiple of
101 Kilobytes, Megabytes or Gigabytes
109 options must be specified.
111 If a file is made smaller, its extra data is lost.
112 If a file is made larger,
113 it will be extended as if by writing bytes with the value zero.
114 If the file does not exist,
115 it is created unless the
120 while truncating a file causes space on disk to be freed,
121 extending a file does not cause space to be allocated.
122 To extend a file and actually allocate the space,
123 it is necessary to explicitly write data to it,
124 using (for example) the shell's
126 redirection syntax, or
130 If the operation fails for an argument,
132 will issue a diagnostic
133 and continue processing the remaining arguments.
141 utility conforms to no known standards.
145 utility first appeared in
150 utility was written by
152 .Aq sheldonh@starjuice.net .