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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 extended part (hole) reads as zero bytes.

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


display this help and exit


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 (powers of 1024) or KB,MB,... (powers of 1000).

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.


Written by Padraig Brady.


GNU coreutils online help: <>
Report truncate translation bugs to <>


Copyright © 2017 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <>.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.


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

Full documentation at: <>
or available locally via: info '(coreutils) truncate invocation'