Login or Register to Ask a Question and Join Our Community

Sponsored Content
Full Discussion: String editing using sed? awk?
Homework and Emergencies Homework & Coursework Questions String editing using sed? awk? Post 302370938 by bakunin on Friday 13th of November 2009 01:36:45 AM
Old 11-13-2009
Carefully analyze the difference between what you have done before and what you are doing now and you will understand whats wrong yourself:

Code:
cat test1 | while read line

versus

Code:
cat test1 | read line

"cat test1" is a process, yes? It has some output, which you can observe by issuing this command, it will print the content of the file, line by line.

Now you pipe the output of this process into another process, which is set up by "while ... do .... done". To the outside this counts as one process, even if it contains several other processes inside.

In the second case you pipe the output into a completely different process, a command called "read", which tries to fill a variable with content. In the first case "read" is only invoked by the while-loop as a sub-process and is presented one line after the other which it dutifully assigns to the variable $line. In the second case it is fed the whole output of the first process at once. What is poor "read" supposed to do, hm?

bakunin
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Editing File using awk/sed

Hello Awk Gurus, Can anyone of you help me with the below problem. I have got a file having data in below format pmFaultyTransportBlocks ----------------------- 9842993 pmFrmNoOfDiscRachFrames ----------------------- NULL pmNoRecRandomAccSuccess -----------------------... (4 Replies)
Discussion started by: Mohammed
4 Replies

2. Shell Programming and Scripting

awk/sed - getting string instead of number

Hi! I am writing a script handling downloading list of files and I have to check whether file is present locally and if not finished than continue downloading. To do so I have to compare sizes of remote file and local file. To check remote file size I have to parse something like this: ... (2 Replies)
Discussion started by: hrwath
2 Replies

3. Shell Programming and Scripting

sed or awk editing help

Hi all I use aix (sadly). I've got a file consisting of fields separated by commas, I need a sed or awk command that will delete all spaces between two commas as long as there are only spaces between the commas. eg ,abc, ,sd , ,dr at would become ,abc,,sd ,,dr at I have... (53 Replies)
Discussion started by: mychmose
53 Replies

4. Shell Programming and Scripting

Line/Variable Editing for Awk sed Cut

Hello, i have a file, i open the file and read the line, i want to get the first item in the csv file and also teh third+6 item and wirte it to a new csv file. only problem is that using echo it takes TOO LONG: please help a newbie. below is my code: WorkingDir=$1 FileName=`cut -d ',' -f... (2 Replies)
Discussion started by: limamichelle
2 Replies

5. Shell Programming and Scripting

match string exactly with awk/sed

Hi all, I have a list that I would like to parse with awk/sed. The list is contains entries such as: JournalTitle: Biochemistry JournalTitle: Biochemistry and cell biology = Biochimie et biologie cellulaire JournalTitle: Biochemistry and experimental biology JournalTitle: Biochemistry and... (6 Replies)
Discussion started by: euval
6 Replies

6. Shell Programming and Scripting

editing file with awk cut and sed

HI All, I am new to unix. I have a file would like to do some editing by using awk, cut and sed. Could anyone help? This file contain 100 lines. There are one line for example: 2,"102343454",5060,"579668","579668","579668","SIP",,,"825922","035885221283026",1,268,"00:59:00.782 APR 17... (2 Replies)
Discussion started by: mimilaw
2 Replies

7. Shell Programming and Scripting

sed or awk command to replace a string pattern with another string based on position of this string

here is what i want to achieve... consider a file contains below contents. the file size is large about 60mb cat dump.sql INSERT INTO `table1` (`id`, `action`, `date`, `descrip`, `lastModified`) VALUES (1,'Change','2011-05-05 00:00:00','Account Updated','2012-02-10... (10 Replies)
Discussion started by: vivek d r
10 Replies

8. Shell Programming and Scripting

sed awk to remove the , in a string

Dear All, Can anyone help to remove the , bewteen "" in a string by using sed or awk? e.g. input : 1,4,5,"abcdef","we,are,here",4,"help hep" output:1,4,5,"abcdef","wearehere",4,"help hep" Thanks, Mimi (5 Replies)
Discussion started by: mimilaw
5 Replies

9. Shell Programming and Scripting

Replace string in XML file with awk/sed with string from another

Sorry for the long/weird title but I'm stuck on a problem I have. I have this XML file: </member> <member> <name>TransactionID</name> <value><string>123456789123456</string></value> </member> <member> <name>Number</name> ... (9 Replies)
Discussion started by: cozzin
9 Replies

10. Shell Programming and Scripting

Replace string of a file with a string of another file for matches using grep,sed,awk

I have a file comp.pkglist which mention package version and release . In 'version change' and 'release change' line there are two versions 'old' and 'new' Version Change: --> Release Change: --> cat comp.pkglist Package list: nss-util-devel-3.28.4-1.el6_9.x86_64 Version Change: 3.28.4 -->... (1 Reply)
Discussion started by: Paras Pandey
1 Replies

LEARN ABOUT OSF1

learn

learn(1)						      General Commands Manual							  learn(1)

NAME

       learn - Provides computer-aided instruction for the C shell

SYNOPSIS

       learn [-directory] [subject] [lesson]

       The learn command provides computer-aided instruction courses and practice in the use of Tru64 UNIX.

OPTIONS

       Allows you to exercise a script in a nonstandard place.

DESCRIPTION

       To  get	started,  enter learn; if this is the first time that you are invoking the learn command, you are guided through a series of ques-
       tions to determine what type of instruction you want to receive.

       If you have used learn before and left your last session without completing a subject, the program uses information  in	$HOME/.learnrc	to
       start you up in the same place you left off.

       To  bypass questions, enter a subject or lesson.  In order to enter a lesson, you must know the lesson number that you received in a previ-
       ous learn command session. If you do not know the lesson number, enter the lesson number as a subject.  The learn command searches for  the
       first  lesson  containing  the subject you specified. If the lesson is a - (dash), learn prompts for each lesson; this is useful for debug-
       ging.

       You can specify the following subjects:

       files editor vi morefiles macros eqn C

SUBCOMMANDS

       There are a few special commands.  The bye command terminates a learn session, and the where command tells you of your  progress  (where  m
       tells  you more.)  The again command redisplays the text of the lesson and again lesson lets you review lesson. The hint command prints the
       last part of the lesson script used to evaluate a response, while hint m prints the entire lesson script.  This	is  useful  for  debugging
       lessons and might possibly give you an idea about what is expected.

EXAMPLES

       To take the online lesson about files, enter: learn files

       You are then prompted for further input.

FILES

       Playpen directories.  Start-up information.

SEE ALSO

       Commands:  csh(1), ex(1)

																	  learn(1)
All times are GMT -4. The time now is 01:00 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy