Sponsored Content
Top Forums Shell Programming and Scripting grep/fgrep/egrep for a very large matrix Post 302423108 by jim mcnamara on Thursday 20th of May 2010 07:37:59 AM
Old 05-20-2010
simply reading 100GB is going to take several minutes, so you should get everything you need on one pass thru the file. If you read through the entire file 200 times you are doomed to wait for looong time.

Actually, you can "tune" a regex. You can also use awk with a regex. awk can output simultaneously to OPEN_MAX differentt files.
Code:
 getconf OPEN_MAX

show us what your input is like and what you want as output.
 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

I need help with fgrep or grep

How can I do an and condition with fgrep. I want to do: ps -ef | fgrep -f searchvalues > tempmail.file mailx -s "Email Subject" email@domain.com < tempmail.file The search values file contains: opt/bea.*java.*80 mysqld What I want is to find things that contain: mysqld OR... (7 Replies)
Discussion started by: jimmy
7 Replies

2. UNIX Desktop Questions & Answers

Difference grep, egrep and fgrep

Hi All, Can anyone please explain me the difference between grep, egrep and fgrep with examples. I am new to unix environment.. Your help is highly appreciated. Regards, ravi (2 Replies)
Discussion started by: ravind27
2 Replies

3. UNIX for Dummies Questions & Answers

Difference between grep, egrep & grep -i

Hi All, Please i need to know the difference between grep, egrep & grep -i when used to serach through a file. My platform is SunOS 5.9 & i'm using the korn shell. Regards, - divroro12 - (2 Replies)
Discussion started by: divroro12
2 Replies

4. Shell Programming and Scripting

Fgrep or grep or awk help - scanning for delimiters.

Hi, I'm struggling a little here, so I figured it's time to ask for help. I have a file with a list of several hundred IDs (the hit file- "hitfile.txt"), which is newline delimited, and a much bigger (~500Mb) text file, "FASTA.txt" with several thousand entries, delimited by ">". It's the... (8 Replies)
Discussion started by: Tbox
8 Replies

5. Shell Programming and Scripting

Using grep or egrep

So a few months ago, I decided to move away from using grep and decided to use egrep in this code that i'm writing. i figured egrep is more robust than grep. well, it appears it isn't. when i used egrep to search the log file for a script that looked like the following, egrep couldn't find... (3 Replies)
Discussion started by: SkySmart
3 Replies

6. Homework & Coursework Questions

grep and egrep

Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted! 1. The problem statement, all variables and given/known data: I have a text file. 1) How do I search for x and y? 'Find all lines that contain David and Emily' 2) How do I... (1 Reply)
Discussion started by: ninjagod123
1 Replies

7. Shell Programming and Scripting

help printing two consecutive columns, every twenty in a large matrix

Hi, I'm having a problem printing two consecutive columns, as I iterate through a large matrix by twenty columns and I was looking for a solution. My input file looks something like this 1 id1 A1 A2 A3 A4 A5 A6....A20 A21 A22 A23....A4001 A4002 2 id2 B1 B2 B3 B4 B5 B6... 3 id3 ... 4 id4... (8 Replies)
Discussion started by: flotsam
8 Replies

8. Shell Programming and Scripting

Fgrep/grep -f and literal strings

I have a file like this: cat file name = server jobname = 1010 snapshot_name = funky_Win2k12_20140213210409 I'm trying to use grep to isolate that first line (name = server), but grep -f "name = " file as well as fgrep "name = " file returns all 3 lines. How do I return... (1 Reply)
Discussion started by: ampsys
1 Replies

9. UNIX for Advanced & Expert Users

Need to use fgrep and egrep in a single command

I have a source file which is something like : C/*M/ / ***HMACCT ** MONTH FOR CURRENT MINUS 14 CAL DAY C/*D/ / ***HMACCT ** DAY FOR CURRENT MINUS 14 CAL DAY C/*X/ / ***HMACCT ** CENTURY FOR CURRENT MINUS 14 CAL DAY C/*Y/ / ***HMACCT **... (5 Replies)
Discussion started by: gotamp
5 Replies

10. Shell Programming and Scripting

Parsing a subset of data from a large matrix

I do have a large matrix of the following format and it is tab delimited ch-ab1-20 ch-bb2-23 ch-ab1-34 ch-ab1-24 er-cc1-45 bv-cc1-78 ch-ab1-20 0 2 3 4 5 6 ch-bb2-23 3 0 5 ... (6 Replies)
Discussion started by: Kanja
6 Replies
English(3pm)						 Perl Programmers Reference Guide					      English(3pm)

NAME
English - use nice English (or awk) names for ugly punctuation variables SYNOPSIS
use English; use English qw( -no_match_vars ) ; # Avoids regex performance penalty # in perl 5.16 and earlier ... if ($ERRNO =~ /denied/) { ... } DESCRIPTION
This module provides aliases for the built-in variables whose names no one seems to like to read. Variables with side-effects which get triggered just by accessing them (like $0) will still be affected. For those variables that have an awk version, both long and short English alternatives are provided. For example, the $/ variable can be referred to either $RS or $INPUT_RECORD_SEPARATOR if you are using the English module. See perlvar for a complete list of these. PERFORMANCE
NOTE: This was fixed in perl 5.20. Mentioning these three variables no longer makes a speed difference. This section still applies if your code is to run on perl 5.18 or earlier. This module can provoke sizeable inefficiencies for regular expressions, due to unfortunate implementation details. If performance matters in your application and you don't need $PREMATCH, $MATCH, or $POSTMATCH, try doing use English qw( -no_match_vars ) ; . It is especially important to do this in modules to avoid penalizing all applications which use them. perl v5.18.2 2014-01-06 English(3pm)
All times are GMT -4. The time now is 08:46 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy