14.5 truncate: Shrink or extend the size of a file

truncate shrinks or extends the size of each file to the specified size. Synopsis:

truncate option… file…

Any file that does not exist is created.

If a file is larger than the specified size, the extra data is lost. If a file is shorter, it is extended and the extended part (or hole) reads as zero bytes.

The program accepts the following options. Also see Common options.

‘-c’

‘--no-create’

Do not create files that do not exist.

‘-o’

‘--io-blocks’

Treat size as number of I/O blocks of the file rather than bytes.

‘-r rfile’

‘--reference=rfile’

Base the size of each file on the size of rfile.

‘-s size’

‘--size=size’

Set or adjust the size of each file according to size. size is in bytes unless --io-blocks is specified. size may be, or may be an integer optionally followed by, one of the following multiplicative suffixes:

‘KB’ =>           1000 (KiloBytes)
‘K’  =>           1024 (KibiBytes)
‘MB’ =>      1000*1000 (MegaBytes)
‘M’  =>      1024*1024 (MebiBytes)
‘GB’ => 1000*1000*1000 (GigaBytes)
‘G’  => 1024*1024*1024 (GibiBytes)

and so on for ‘T’, ‘P’, ‘E’, ‘Z’, and ‘Y’.

size may also be prefixed by one of the following to adjust the size of each file based on its current size:

‘+’  => extend by
‘-’  => reduce by
‘<’  => at most
‘>’  => at least
‘/’  => round down to multiple of
‘%’  => round up to multiple of

An exit status of zero indicates success, and a nonzero value indicates failure.