truncate - shrink or extend the size of a file to the specified size

truncate OPTION... FILE...

Shrink or extend the size of each FILE to the specified size

A FILE argument 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 (hole) reads as zero bytes.

Mandatory arguments to long options are mandatory for short options too.

-c, --no-create

do not create any files

-o, --io-blocks

treat SIZE as number of IO blocks instead of bytes

-r, --reference=RFILE

base size on RFILE

-s, --size=SIZE

set or adjust the file size by SIZE bytes

--help

display this help and exit

--version

output version information and exit

The SIZE argument is an integer and optional unit (example: 10K is 10*1024). Units are K,M,G,T,P,E,Z,Y,R,Q (powers of 1024) or KB,MB,... (powers of 1000). Binary prefixes can be used, too: KiB=K, MiB=M, and so on.

SIZE may also be prefixed by one of the following modifying characters: '+' extend by, '-' reduce by, '<' at most, '>' at least, '/' round down to multiple of, '%' round up to multiple of.

dd(1), truncate(2), ftruncate(2)

Full documentation <https://www.gnu.org/software/coreutils/truncate>
or available locally via: info '(coreutils) truncate invocation'