Sponsored Content
Top Forums UNIX for Beginners Questions & Answers Grep first n lines from each file Post 303046256 by vgersh99 on Tuesday 28th of April 2020 10:05:08 AM
Old 04-28-2020
man head
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Grep multiple lines from a file

Hi, I would like to ask if there is any method to grep a chuck of lines based on the latest file in a directory. E.g Latest file in the directory: Line 1: 532243 Line 2: 123456 Line 3: 334566 Line 4: 44567545 I wanted to grep all the line after line 2 i.e. Line 3 and line 4 and... (5 Replies)
Discussion started by: dwgi32
5 Replies

2. Shell Programming and Scripting

grep and display lines from a file

I have to grep on a few words in a file and then display the line containing those words and the line above it. For ex - File1.txt contains... abc xyz abc This is a test Test successful abc xyz abc Just a test Test successful I find the words 'Test successful' in the file... (6 Replies)
Discussion started by: user7617
6 Replies

3. Shell Programming and Scripting

grep two lines in a file

Hi Everyone, I have 1.txt 1 6-6 3-3 word y f 6-6 word 5-5 4 5-5 word The output should be: 3-3 (8 Replies)
Discussion started by: jimmy_y
8 Replies

4. Shell Programming and Scripting

Grep between block of lines in a file

Hi Friends, I have a file which has many of the statements like below ******** MAKING > noun1 < cg_all statements statements statements ********* MAKING > noun2 < cg_all statements statements statements ********* MAKING > noun3 < all statements statements statements I would... (3 Replies)
Discussion started by: ganga.dharan
3 Replies

5. Shell Programming and Scripting

Extracting specific lines of data from a file and related lines of data based on a grep value range?

Hi, I have one file, say file 1, that has data like below where 19900107 is the date, 19900107 12 144 129 0.7380047 19900108 12 168 129 0.3149017 19900109 12 192 129 3.2766666E-02 ... (3 Replies)
Discussion started by: Wynner
3 Replies

6. UNIX for Dummies Questions & Answers

grep two lines from a file

Sample File abc xyz def abc ggh abc xyz I just created a sample file above to show what I need. I need to grep two lines. e.g abc and xyz(only if they are one after the other) so output would be abc xyz abc xyz (note abc followed by ggh line would not come out in the output). I... (9 Replies)
Discussion started by: ran123
9 Replies

7. UNIX for Dummies Questions & Answers

grep lines in a file that have only one field

Hello. How does one grep lines in a file that have only one field? AAA BBB CCC DDD AAA CCC Is is possible to grep "DDD" becuase it has only one field? Thanks. ---------- Post updated at 08:03 PM ---------- Previous update was at 07:25 PM ---------- I found it, thank you! awk 'NF... (2 Replies)
Discussion started by: jimmyf
2 Replies

8. Shell Programming and Scripting

Grep 3 lines from a file

I have file, test.txt UtranCellId MDN407WI1 administrativeState 1 (UNLOCKED) aseDlAdm 500 aseUlAdm 800 cellReserved 1 (NOT_RESERVED) dlCodeAdm ... (6 Replies)
Discussion started by: radius
6 Replies

9. Shell Programming and Scripting

Grep into a file + show following lines

Hi guys, This is probably very easy but I've no idea how to pull this out. Basically, I need to find errors into a very large logfile. When you grep the ID, the output is like this: +- Type: 799911 Code: Ret: 22728954 Mand: X Def: Des: UserDes: SeqNo: 2 +- Type: 799911 Code: Ret:... (5 Replies)
Discussion started by: Arkadia
5 Replies

10. Shell Programming and Scripting

Grep the lines in one file that are also in another

Hi all, I have two files. File A looks like this: abkhasian com|hum accent com|com|com|com|sta acceptation act|com|sta adventures com|hum adversity com|hum|hum and File B looks like this: adventure adventures adversary Adverse adversity I want to print those lines in File A... (9 Replies)
Discussion started by: owwow14
9 Replies
POE::Filter::Grep(3pm)					User Contributed Perl Documentation				    POE::Filter::Grep(3pm)

NAME
POE::Filter::Grep - select or remove items based on simple rules SYNOPSIS
#!perl use POE qw( Wheel::FollowTail Filter::Line Filter::Grep Filter::Stackable ); POE::Session->create( inline_states => { _start => sub { my $parse_input_as_lines = POE::Filter::Line->new(); my $select_sudo_log_lines = POE::Filter::Grep->new( Put => sub { 1 }, Get => sub { my $input = shift; return $input =~ /sudo[d+]/i; }, ); my $filter_stack = POE::Filter::Stackable->new( Filters => [ $parse_input_as_lines, # first on get, last on put $select_sudo_log_lines, # first on put, last on get ] ); $_[HEAP]{tailor} = POE::Wheel::FollowTail->new( Filename => "/var/log/system.log", InputEvent => "got_log_line", Filter => $filter_stack, ); }, got_log_line => sub { print "Log: $_[ARG0] "; } } ); POE::Kernel->run(); exit; DESCRIPTION
POE::Filter::Grep selects or removes items based on simple tests. It may be used to filter input, output, or both. This filter is named and modeled after Perl's built-in grep() function. POE::Filter::Grep is designed to be combined with other filters through POE::Filter::Stackable. In the "SYNOPSIS" example, a filter stack is created to parse logs as lines and remove all entries that don't pertain to a sudo process. (Or if your glass is half full, the stack only selects entries that DO mention sudo.) PUBLIC FILTER METHODS
In addition to the usual POE::Filter methods, POE::Filter::Grep also supports the following. new new() constructs a new POE::Filter::Grep object. It must either be called with a single Code parameter, or both a Put and a Get parameter. The values for Code, Put, and Get are code references that, when invoked, return true to select an item or false to reject it. A Code function will be used for both input and output, while Get and Put functions allow input and output to be filtered in different ways. The item in question will be passed as the function's sole parameter. sub reject_bidoofs { my $pokemon = shift; return 1 if $pokemon ne "bidoof"; return; } my $gotta_catch_nearly_all = POE::Filter::Grep->new( Code => &reject_bidoofs, ); Enforce read-only behavior: my $read_only = POE::Filter::Grep->new( Get => sub { 1 }, Put => sub { 0 }, ); modify modify() changes a POE::Filter::Grep object's behavior at run-time. It accepts the same parameters as new(), and it replaces the existing tests with new ones. # Don't give away our Dialgas. $gotta_catch_nearly_all->modify( Get => sub { 1 }, Put => sub { return shift() ne "dialga" }, ); SEE ALSO
POE::Filter for more information about filters in general. POE::Filter::Stackable for more details on stacking filters. BUGS
None known. AUTHORS &; COPYRIGHTS The Grep filter was contributed by Dieter Pearcey. Documentation is provided by Rocco Caputo. Please see the POE manpage for more information about authors and contributors. perl v5.14.2 2012-05-15 POE::Filter::Grep(3pm)
All times are GMT -4. The time now is 07:05 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy