Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: Perl - Use of *? in Matching Pattern
Top Forums Shell Programming and Scripting Perl - Use of *? in Matching Pattern Post 302945220 by jnrohit2k on Wednesday 27th of May 2015 10:44:01 AM
Old 05-27-2015
Perl - Use of *? in Matching Pattern
I am using Perl version 5.8.4 and trying to understand the use of regular expression. Following is my code and output.

Code:
 
 $string = "Perl is a\nScripting language";
 ($start) = ($string =~ /\A(.*?) /);
 @lines = ($string =~ /^(.*?) /gm);
 print "First Word (using \\A): $start\n","Line Starts (using ^): @lines\n";

Output:-
First Word (using \A): Perl
Line Starts (using ^): Perl Scripting

I know
* (star) is used to 'Matches 0 or more occurrence of preceding expression'.
? (question mark) is used to 'Matches 0 or 1 occurrence of preceding expression'.

But I did not understand how both (*?) are working together in above piece of code.

Thanks!
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

pattern matching + perl question

i can only find the first occurance of a pattern how do i set it to loop untill all occurances have changed. #! /usr/bin/perl use POSIX; open (DFH_FILE, "./dfh") or die "Can not read file ($!)"; foreach (<DFH_FILE>) { if ($_ !~ /^#|^$/) { chomp; ... (1 Reply)
Discussion started by: Optimus_P
1 Replies

2. Shell Programming and Scripting

perl pattern matching

hi i am trying to get digits inside brackes from file , whose structure is defined below CREATE TABLE TELM (SOC_NO CHAR (3) NOT NULL, TXN_AMOUNT NUMBER (17,3) SIGN_ON_TIME CHAR (8) TELLER_APP_LIMIT NUMBER (17,3) FIL01 ... (2 Replies)
Discussion started by: zedex
2 Replies

3. Shell Programming and Scripting

Perl Pattern Matching !!! Help

Hello I got the below one from in one of this forums For Ex: Loading File System Networking in nature now i need to extract the patterns between the words File and Networking : i.e. sample output: System cmd used : cat <file> | sed 's/.*File //' | sed 's/Closing.*$//' Actually... (0 Replies)
Discussion started by: maxmave
0 Replies

4. Shell Programming and Scripting

Perl -Pattern Matching help..!

Hi, I got doubt in Pattern matching, could you tell me how the following differs in action ?? if ( $line1==/$line2/ ) if ( $line1=~/$line2/ ) if ( $line1=~m/$line2/) What is the significance of '~' in matching. Thanks in advance CoolBhai (5 Replies)
Discussion started by: coolbhai
5 Replies

5. Shell Programming and Scripting

Perl Pattern Matching

Hello experts, I have a file containing the following text(shortened here). File Begin ---------- < # Billboard.d3fc1302a677.imagePath=S:\\efcm_T4 < Billboard.d3fc1302a677.imagePath=S:\\efcm_T4 --- > # Billboard.d3fc1302a677.imagePath=S:\\efcm_Cassini >... (2 Replies)
Discussion started by: nmattam
2 Replies

6. Shell Programming and Scripting

Perl pattern matching!!

Hi experts, I have many occurances of the following headers in a file. I need to grep for the word changed/inserted in the header, calculate the difference between the two numbers and list the count incrementally. Headers in a file look like this: ------------------- ---------------------... (6 Replies)
Discussion started by: nmattam
6 Replies

7. Shell Programming and Scripting

Perl Pattern matching...

I am doing a file patterhn matching for a text file in PERL I am using this,,, but it says that no file is found $filepattern = '\d{1,4}.*A0NW9693.NDM.HBIDT.*.AD34XADJ.txt'; Can anyone help me out with Perl Pattern Matching concepts and how to do pattern matching for this txt file:... (4 Replies)
Discussion started by: msrahman
4 Replies

8. Shell Programming and Scripting

Pattern Matching in PERL

I have a 2 files in .gz format and it consists of 5 million lines the format of the file would be gzcat file1.gz | more abcde aerere ffgh56 .. .. 12345 gzcat file2.gz | more abcde , 12345 , 67890, ffgh56 , 45623 ,12334 whatever the string is in the file1 should be matched... (3 Replies)
Discussion started by: aravindj80
3 Replies

9. Shell Programming and Scripting

Need help with perl pattern matching

My log file looks as given below, its actually a huge file around 1 GB and these are some of the line: conn=5368758 op=10628050 msgId=64 - RESULT err=0 tag=101 nentries=1 etime=0 conn=7462122 op=-1 msgId=-1 - fd=247 slot=247 LDAPS connection from 10.13.18.12:37645 to 10.18.6.45 conn=7462122... (5 Replies)
Discussion started by: sags007_99
5 Replies

10. Shell Programming and Scripting

Pattern matching in Perl

Hi, I have a list of IP, eg : 192.168.0.15 192.168.0.24 192.168.2.110 192.168.2.200 And I would like the shortest pattern who match with '192.168.0' and '192.168.2' (without the last dot and number). (7 Replies)
Discussion started by: X-Or
7 Replies

LEARN ABOUT MINIX

ppmtosixel

ppmtosixel(1)                                                 General Commands Manual                                                ppmtosixel(1)

NAME

       ppmtosixel - convert a portable pixmap into DEC sixel format

SYNOPSIS

       ppmtosixel [-raw] [-margin] [ppmfile]

DESCRIPTION

       Reads  a  portable  pixmap  as input.  Produces sixel commands (SIX) as output.  The output is formatted for color printing, e.g. for a DEC
       LJ250 color inkjet printer.

       If RGB values from the PPM file do not have maxval=100, the RGB values are rescaled.  A printer control header and a color assignment table
       begin the SIX file.  Image data is written in a compressed format by default.  A printer control footer ends the image file.

OPTIONS

       -raw   If  specified,  each  pixel  will  be explicitly described in the image file.  If -raw is not specified, output will default to com-
              pressed format in which identical adjacent pixels are replaced by "repeat pixel" commands.  A raw file is often an order  of  magni-
              tude larger than a compressed file and prints much slower.

       -margin
              If  -margin  is not specified, the image will be start at the left margin (of the window, paper, or whatever).  If -margin is speci-
              fied, a 1.5 inch left margin will offset the image.

PRINTING

       Generally, sixel files must reach the printer unfiltered.  Use the lpr -x option or cat filename > /dev/tty0?.

BUGS

       Upon rescaling, truncation of the least significant bits of RGB values may result in poor color conversion.  If the original PPM maxval was
       greater  than  100,  rescaling  also reduces the image depth.  While the actual RGB values from the ppm file are more or less retained, the
       color palette of the LJ250 may not match the colors on your screen.  This seems to be a printer limitation.

SEE ALSO

       ppm(5)

AUTHOR

       Copyright (C) 1991 by Rick Vinci.

                                                                   26 April 1991                                                     ppmtosixel(1)
All times are GMT -4. The time now is 02:08 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy