• Start
• Documentation
  • PostgreSQL
  • mnoGoSearch
  • Apache 2.4
  • FreeBSD handbook
  • FreeBSD Manual
  • FreeBSD Source
• Tools
• Search
• Protected Area

plain

FreeBSD manual

keyword 1 2 3 4 5 6 7 8 9 n l

download PDF document: truncate.1.pdf

TRUNCATE(1) FreeBSD General Commands Manual TRUNCATE(1)
NAME truncate - truncate, extend the length of files, or perform space management in files
SYNOPSIS truncate [-c] -s [+|-|%|/]size[SUFFIX] file ... truncate [-c] -r rfile file ... truncate [-c] -d [-o offset[SUFFIX]] -l length[SUFFIX] file ...
DESCRIPTION The truncate utility adjusts the length of each regular file given on the command-line, or performs space management with the given offset and the length over a 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[SUFFIX] 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.
-d Zero a region in the specified file. If the underlying file system of the given file supports hole-punching, file system space deallocation may be performed in the operation region.
-o offset The space management operation is performed at the given offset bytes in the file. If this option is not specified, the operation is performed at the beginning of the file.
-l length The length of the operation range in bytes. This option must always be specified if option -d is specified, and must be greater than 0.
The size, offset and length arguments 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, -s and -d options must be specified.
If a file is made smaller, its extra data is lost. If a file is made 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), fspacectl(2), 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>. Hole-punching support of this utility was developed by Ka Ho Ng <khng@FreeBSD.org>.
FreeBSD 14.0-RELEASE-p11 August 19, 2021 FreeBSD 14.0-RELEASE-p11