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 sparse 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’, ‘Y’, ‘R’, and ‘Q’. Binary prefixes can be used, too: ‘KiB’=‘K’, ‘MiB’=‘M’, and so on.

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.