TRUNCATE(1)             FreeBSD General Commands Manual            TRUNCATE(1)

NAME
     truncate - truncate or extend the length of files

SYNOPSIS
     truncate [-c] -s [+|-|%|/]size[K|k|M|m|G|g|T|t] file ...
     truncate [-c] -r rfile file ...

DESCRIPTION
     The truncate utility adjusts the length of each regular file given on the
     command-line.

     The following options are available:

     -c      Do not create files if they do not exist.  The truncate utility
             does not treat this as an error.  No error messages are displayed
             and the exit value is not affected.

     -r rfile
             Truncate or extend files to the length of the file rfile.

     -s [+|-|%|/]size[K|k|M|m|G|g|T|t]
             If the size argument is preceded by a plus sign (+), files will
             be extended by this number of bytes.  If the size argument is
             preceded by a dash (-), file lengths will be reduced by no more
             than this number of bytes, to a minimum length of zero bytes.  If
             the size argument is preceded by a percent sign (%), files will
             be round up to a multiple of this number of bytes.  If the size
             argument is preceded by a slash sign (/), files will be round
             down to a multiple of this number of bytes, to a minimum length
             of zero bytes.  Otherwise, the size argument specifies an
             absolute length to which all files should be extended or reduced
             as appropriate.

             The size argument may be suffixed with one of K, M, G or T
             (either upper or lower case) to indicate a multiple of Kilobytes,
             Megabytes, Gigabytes or Terabytes respectively.

     Exactly one of the -r and -s options must be specified.

     If a file is made smaller, its extra data is lost.  If a file is made
     larger, it will be extended as if by writing bytes with the value zero.
     If the file does not exist, it is created unless the -c option is
     specified.

     Note that, while truncating a file causes space on disk to be freed,
     extending a file does not cause space to be allocated.  To extend a file
     and actually allocate the space, it is necessary to explicitly write data
     to it, using (for example) the shell's `>>' redirection syntax, or dd(1).

EXIT STATUS
     The truncate utility exits 0 on success, and >0 if an error occurs.  If
     the operation fails for an argument, truncate will issue a diagnostic and
     continue processing the remaining arguments.

EXAMPLES
     Adjust the size of the file test_file to 10 Megabytes but do not create
     it if it does not exist:

           truncate -c -s +10M test_file

     Same as above but create the file if it does not exist:

           truncate -s +10M test_file
           ls -l test_file
           -rw-r--r--  1 root  wheel  10485760 Jul 22 18:48 test_file

     Adjust the size of test_file to the size of the kernel and create another
     file test_file2 with the same size:

           truncate -r /boot/kernel/kernel test_file test_file2
           ls -l /boot/kernel/kernel test_file*
           -r-xr-xr-x  1 root  wheel    31352552 May 15 14:18 /boot/kernel/kernel*
           -rw-r--r--  1 root  wheel    31352552 Jul 22 19:15 test_file
           -rw-r--r--  1 root  wheel    31352552 Jul 22 19:15 test_file2

     Downsize test_file in 5 Megabytes:

           # truncate -s -5M test_file
           ls -l test_file*
           -rw-r--r--  1 root  wheel    26109672 Jul 22 19:17 test_file
           -rw-r--r--  1 root  wheel    31352552 Jul 22 19:15 test_file2

SEE ALSO
     dd(1), touch(1), truncate(2)

STANDARDS
     The truncate utility conforms to no known standards.

HISTORY
     The truncate utility first appeared in FreeBSD 4.2.

AUTHORS
     The truncate utility was written by Sheldon Hearn
     <sheldonh@starjuice.net>.

FreeBSD 13.1-RELEASE-p6          July 27, 2020         FreeBSD 13.1-RELEASE-p6