10 More Discussions You Might Find Interesting
1. Solaris
I have recently built a new server and patched Soalris 10 up tp latest bundle etc...
When I run a decompress using the format zcat fred.Z |tar -xvf - it runs at a very slow rate.
A similiar server which is less powerful runs over twice as quick.
Is there any work arounds to configure decompress... (4 Replies)
Discussion started by: smcart
4 Replies
2. Shell Programming and Scripting
Hello,
When i lauches this command
ssh -n server_name gunzip -c "/REP/xxxx.gz" > server.logThere are a few stray characters like NULNULNULNUL100644 NUL000000NUL000000NUL00024002704 12135060747 012607NUL at the beginning of server.log.
In the xxxx.gz there is a tar file
I'm not sure but it... (5 Replies)
Discussion started by: amazigh42
5 Replies
3. Shell Programming and Scripting
I have a tar file which i want to read and check some specific fields basis on which i want to get output.
Code
zcat samplefile.tar.gz | awk 'FNR==1 {++counter}
counter ==2 {BB=1;next}
substr($0,26,2) =="01") {next}
(substr($0,28,12) ~ "^") {next}
(substr($0,184,3) in BB) {next}
1
'... (7 Replies)
Discussion started by: siramitsharma
7 Replies
4. Shell Programming and Scripting
I created a backup script that emails all the admins when the backup is complete and attaches a log file of what what backed up. On occasion, something happens in which the backups stop working, I started "grep"ing around /var/log/syslog and I usually find the smoking gun. My goal is to zcat... (8 Replies)
Discussion started by: metallica1973
8 Replies
5. Shell Programming and Scripting
Hi,
Like
cat file1 file2 > file
Can I do
zcat file1.gz file2.gz > file.gz (11 Replies)
Discussion started by: jacobs.smith
11 Replies
6. UNIX for Advanced & Expert Users
I have a program............
#include<stdio.h>
#include<unistd.h>
main()
{
if(fork == 0)
{
printf("Hi every body:p!!!!!!!!!!");
}
}
This program works with out any error. here fork is not a system call. It just act as a variable.But how it works without declaring it? What data type it... (19 Replies)
Discussion started by: carolsanjeevi
19 Replies
7. Programming
pls explain me how this works....
DECODE (SUBSTR (field, 1, 1),'''', '''''' || field || '''','''' || field || '''')
here field is a column in an oracle table.... (7 Replies)
Discussion started by: vijay_0209
7 Replies
8. Linux
Hi
I am trying to extract a <filename>.tar.Z on a SLES machine using zcat.
The command I am using is
zcat <filename>.tar.Z | tar xf -
When I use the above I get the following message
tar: Read 7168 bytes from -
I think the message is benign because I see that my files where... (2 Replies)
Discussion started by: felixmat1
2 Replies
9. UNIX for Dummies Questions & Answers
ls displays files in tabbed output. Say a directory contains 3 files. ls will list all 3 in one line. So, I expect ls | wc -l to give 1, but it counts the nr of files and gives 3.
Can someone explain how this works? (3 Replies)
Discussion started by: krishmaths
3 Replies
10. UNIX for Dummies Questions & Answers
Hi all
I have more than 1000 files in a folder and when ever i use a "compress" or "zcat" command it give error
/bin/zcat: Arg list too long. .
any solution for this :o (3 Replies)
Discussion started by: muneebr
3 Replies
COMPRESS(1) General Commands Manual COMPRESS(1)
NAME
compress, uncompress, zcat - compress and expand data
SYNOPSIS
compress [ -f ] [ -v ] [ -c ] [ -b bits ] [ name ... ]
uncompress [ -f ] [ -v ] [ -c ] [ name ... ]
zcat [ name ... ]
DESCRIPTION
Compress reduces the size of the named files using adaptive Lempel-Ziv coding. Whenever possible, each file is replaced by one with the
extension .Z, while keeping the same ownership modes, access and modification times. If no files are specified, the standard input is com-
pressed to the standard output. Compressed files can be restored to their original form using uncompress or zcat.
The -f option will force compression of name, even if it does not actually shrink or the corresponding name.Z file already exists. Except
when run in the background under /bin/sh, if -f is not given the user is prompted as to whether an existing name.Z file should be overwrit-
ten.
The -c (``cat'') option makes compress/uncompress write to the standard output; no files are changed. The nondestructive behavior of zcat
is identical to that of uncompress -c.
Compress uses the modified Lempel-Ziv algorithm popularized in "A Technique for High Performance Data Compression", Terry A. Welch, IEEE
Computer, vol. 17, no. 6 (June 1984), pp. 8-19. Common substrings in the file are first replaced by 9-bit codes 257 and up. When code 512
is reached, the algorithm switches to 10-bit codes and continues to use more bits until the limit specified by the -b flag is reached
(default 16). Bits must be between 9 and 16. The default can be changed in the source to allow compress to be run on a smaller machine.
After the bits limit is attained, compress periodically checks the compression ratio. If it is increasing, compress continues to use the
existing code dictionary. However, if the compression ratio decreases, compress discards the table of substrings and rebuilds it from
scratch. This allows the algorithm to adapt to the next "block" of the file.
Note that the -b flag is omitted for uncompress, since the bits parameter specified during compression is encoded within the output, along
with a magic number to ensure that neither decompression of random data nor recompression of compressed data is attempted.
The amount of compression obtained depends on the size of the input, the number of bits per code, and the distribution of common sub-
strings. Typically, text such as source code or English is reduced by 50-60%. Compression is generally much better than that achieved by
Huffman coding (as used in pack), or adaptive Huffman coding (compact), and takes less time to compute.
The -v option causes the printing of the percentage reduction of each file.
If an error occurs, exit status is 1, else if the last file was not compressed because it became larger, the status is 2; else the status
is 0.
DIAGNOSTICS
Usage: compress [-fvc] [-b maxbits] [file ...]
Invalid options were specified on the command line.
Missing maxbits
Maxbits must follow -b.
file: not in compressed format
The file specified to uncompress has not been compressed.
file: compressed with xx bits, can only handle yy bits
File was compressed by a program that could deal with more bits than the compress code on this machine. Recompress the file with
smaller bits.
file: already has .Z suffix -- no change
The file is assumed to be already compressed. Rename the file and try again.
file: filename too long to tack on .Z
The file cannot be compressed because its name is longer than 12 characters. Rename and try again. This message does not occur on
BSD systems.
file already exists; do you wish to overwrite (y or n)?
Respond "y" if you want the output file to be replaced; "n" if not.
uncompress: corrupt input
A SIGSEGV violation was detected which usually means that the input file is corrupted.
Compression: xx.xx%
Percentage of the input saved by compression. (Relevant only for -v.)
-- not a regular file: unchanged
When the input file is not a regular file, (e.g. a directory), it is left unaltered.
-- has xx other links: unchanged
The input file has links; it is left unchanged. See ln(1) for more information.
-- file unchanged
No savings is achieved by compression. The input remains virgin.
BUGS
Although compressed files are compatible between machines with large memory, -b12 should be used for file transfer to architectures with a
small process data space (64KB or less, as exhibited by the DEC PDP series, the Intel 80286, etc.)
compress should be more flexible about the existence of the `.Z' suffix.
4.3 Berkeley Distribution May 11, 1986 COMPRESS(1)