11-19-2009
$ commands in unix
What are the various commands which use $ in unix and what do each of these indicate? eg: echo $? returns the success status of the previous commands..similarly $$ returns some numeric value..wat exactly are these?
From where can a download a document which can help me getting more details about this?
Regards,
DDS.
---------- Post updated at 11:47 AM ---------- Previous update was at 11:22 AM ----------
Can someone please get back to me on this? Need this info urgently..
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LEARN ABOUT CENTOS
truncate
TRUNCATE(1) User Commands TRUNCATE(1)
NAME
truncate - shrink or extend the size of a file to the specified size
SYNOPSIS
truncate OPTION... FILE...
DESCRIPTION
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.
-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
SIZE is an integer and optional unit (example: 10M is 10*1024*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.
GNU coreutils online help: <http://www.gnu.org/software/coreutils/> Report truncate translation bugs to <http://translationpro-
ject.org/team/>
AUTHOR
Written by Padraig Brady.
COPYRIGHT
Copyright (C) 2013 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.
SEE ALSO
dd(1), truncate(2), ftruncate(2)
The full documentation for truncate is maintained as a Texinfo manual. If the info and truncate programs are properly installed at your
site, the command
info coreutils 'truncate invocation'
should give you access to the complete manual.
GNU coreutils 8.22 June 2014 TRUNCATE(1)