Visit Our UNIX and Linux User Community


sed,awk


 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting sed,awk
# 1  
Old 06-25-2002
Power sed,awk

Hi,

I know sed is stream text editor and not a bit more than that. Can anyone explain its usage and advantages?

How is awk different from sed?

I donno i am a bit confused about it. But i have coded in awk and shell.


Thanks,
Nisha

Smilie
# 2  
Old 06-25-2002
do you know ?
man Smilie
# 3  
Old 06-25-2002
i aint clear.. what r u trying to say?

-Nisha
# 4  
Old 06-25-2002
This is a very brief diffrences between sed and awk text processing utilities.

sed: a non-interactive text file editor

awk: a field-oriented pattern processing language with a C-like syntax

For all their differences, the two utilities share a similar invocation syntax, both use regular expressions , both read input by default from stdin, and both output to stdout. These are well-behaved UNIX tools, and they work together well. The output from one can be piped into the other, and their combined capabilities give shell scripts some of the power of Perl.

One important difference between the utilities is that while shell scripts can easily pass arguments to sed, it is more complicated for awk.

Note:
Awk is a full-featured text processing language with a syntax reminiscent of C. While it possesses an extensive set of operators and capabilities, we will cover only a couple of these here - the ones most useful for shell scripting.

Awk breaks each line of input passed to it into fields. By default, a field is a string of consecutive characters separated by whitespace, though there are options for changing the delimiter. Awk parses and operates on each separate field. This makes awk ideal for handling structured text files, especially tables, data organized into consistent chunks, such as rows and columns.

Strong quoting (single quotes) and curly brackets enclose segments of awk code within a shell script.

While...

Sed is a non-interactive line editor. It receives text input, whether from stdin or from a file, performs certain operations on specified lines of the input, one line at a time, then outputs the result to stdout or to a file. Within a shell script, sed is usually one of several tool components in a pipe.

Sed determines which lines of its input that it will operate on from the address range passed to it. Specify this address range either by line number or by a pattern to match. For example, 3d signals sed to delete line 3 of the input, and /windows/d tells sed that you want every line of the input containing a match to "windows" deleted.

Of all the operations in the sed toolkit, we will focus primarily on the three most commonly used ones. These are printing (to stdout), deletion, and substitution.
# 5  
Old 06-25-2002
Hi nisha,

man awk
man sed

gives some explanation.
ladwig
# 6  
Old 06-25-2002
Lightbulb

Hi,

Awk can be incorporated in a shell. At the same time it can be written using C. The latter one sounds easy because the syntax for incorporating awk in a shell is difficult. I experienced this practically.

Am i right?

-Nisha
# 7  
Old 06-25-2002
Yes nisha. you are absoulutely rite.

An awk program performs the given operation and consist of one or more awk statements. Following awk program extracts letters sent by a given machine from standard Unix mail file. System has two states, state 0 is searching and state 1 is printing selected mail. Variable p is the state variable. Note, that the end pattern may be part of the start pattern when there are two letters from the selected machine immediately after each other. Thus the order of pattern matching statements is important. If several statements are expected to match the same line, they must be in order of selectivity, most selective last.
Code:
   BEGIN { print FILENAME; p = 0 }
             /From / && / 199/           { p = 0 }
             /From / && /rde.axd.kill.net/  { p = 1 } 
     { if (p > 0) print $0
  END   { print "End ..." }

Hope does give you some idea.

Previous Thread | Next Thread
Test Your Knowledge in Computers #674
Difficulty: Medium
Wi-Fi does not use any parts of the IEEE 803 protocol.
True or False?

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

sed and awk giving error ./sample.sh: line 13: sed: command not found

Hi, I am running a script sample.sh in bash environment .In the script i am using sed and awk commands which when executed individually from terminal they are getting executed normally but when i give these sed and awk commands in the script it is giving the below errors :- ./sample.sh: line... (12 Replies)
Discussion started by: satishmallidi
12 Replies

2. Shell Programming and Scripting

Is this possible using SED and AWK?

Dear Geeks, I want to manipulate a file with certain modifications for that using sed or AWK how to do this process for one file i have this type of data. Input File: "Restricted and Reserved names .ANISH",3798,"TEST.CO",1201208,6/16/10 0:00,6/16/13 0:00,,,"CO","2nd"^M "Restricted and... (4 Replies)
Discussion started by: anishkumarv
4 Replies

3. UNIX for Dummies Questions & Answers

sed/awk or help please

I have a file that contain the data below: B1 1 2 3 B2 20 30 40 B3 7 8 B4 100 B5 21 22 23How can I retrieve the data for B1 into a seperate file. (8 Replies)
Discussion started by: bobo
8 Replies

4. Shell Programming and Scripting

Need help using awk or sed.

Hi All, Is there a way of comparing two columns in the same file and deleting the row if the values of the columns match. I have the sample data file as below. M024900|175309.00|968.00|17 M025001|19861.79|97.90|148 M025002|431.70|159.00|3 M025003|912.30|159.90|6 ... (6 Replies)
Discussion started by: nua7
6 Replies

5. Shell Programming and Scripting

Using sed or awk?

What if I wanted to add a word such as IT after the first character and if theres 3 characters, after the 2nd character? output would be: G, it H G, H it P G, H, P it L I'm thinking that AWK would be the easiest way to do this... Currently looking it up. Right now I'm using awk but I... (13 Replies)
Discussion started by: puttster
13 Replies

6. UNIX for Dummies Questions & Answers

sed or awk?

I've got an inventory database with eight columns with things like product name, manufacturer, UPC code, etc. on each line. Our PO (purchase order) number is in the first column. I can grep the date and get the full line of data but I would like to strip out everything but the PO number in the... (5 Replies)
Discussion started by: NetJones
5 Replies

7. UNIX for Advanced & Expert Users

Awk or Sed help

Hi, I have a data file with 5 columns - like this: "20080401 09:43:08.770798 +0100s","TEST 1","R 1","A TEST","Nov 27 2007","1" "20080401 09:43:08.770798 +0100s","THIS IS A TEST","R 2","B TEST","Nov 30 2007","10" "20080401 09:43:08.770798 +0100s","ANOTHER TEST","R 3","B TEST","Nov 05... (7 Replies)
Discussion started by: MrG-San
7 Replies

8. UNIX for Advanced & Expert Users

sed in awk ? or nested awk ?

Hey all, Can I put sed command inside the awk action ?? If not then can i do grep in the awk action ?? For ex: awk '$1=="174" { ppid=($2) ; sed -n '/$ppid/p' tempfind.txt ; }' tempfind.txt Assume: 174 is string. Assume: tempfind.txt is used for awk and sed both. tempfind.txt... (11 Replies)
Discussion started by: varungupta
11 Replies

9. Shell Programming and Scripting

sed in awk

Hi there, I'm trying to process a comma delimited file to remove the seconds: 916901,0,488589834,TRADE,Trade, ,2002-07-2510:14:43.387,CITI.MW,970847, , , ,808.0,2526.0,0.0,0.0,-1 So basically the .*** from the 7th field Any help appreciated Jon (4 Replies)
Discussion started by: orange_one
4 Replies

10. Shell Programming and Scripting

awk / sed

I have many messages such as the test message below: 00:00000:00021:2002/05/13 13:57:00.51 ERROR:- Test error, my test error!!! I am writing a script in which I need to get everything from the word "ERROR:-" onwards. I normally use awk for these things, but I am not an expert at it so i am... (6 Replies)
Discussion started by: baileyr1
6 Replies

Featured Tech Videos