awk condition


 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting awk condition
# 1  
Old 10-30-2014
awk condition

Hi Gurus,

one of my current script, there is awk statement as below:
Code:
 
awk  '{a[$1]=a[$1]?a[$1]" "$3:$3}END{for (i in a) print i,a[i]}'

I don't understand what's "{a[$1]=a[$1]?a[$1]" "$3:$3}" mean?

can anybody give me a brief explaination.

thanks in advance.
# 2  
Old 10-30-2014
That's what they call "conditional assignment", it's using "?" and ":" to separate the TRUE and FALSE branch:
Code:
a[$1]=      assignment target
a[$1]       logical condition (empty or 0: FALSE; any other value: TRUE)
?           starts TRUE branch
a[$1]" "$3  concatenation of two strings
:           starts FALSE branch
$3          single simple string

man awk is your friend!
This User Gave Thanks to RudiC For This Post:
# 3  
Old 10-30-2014
Hello Ken6503,

Following is the explaination.

a[$1]=a[$1]?a[$1]" "$3:$3
It means we are creating a array whose index is value of $1 and if value of $1 is repeating in the further then we are concatinating the values of all $1 into a single index

Let's say we have a file as follows.

Code:
cat test35
Singh   1       Ravinder        cool
Prince  2       Gurmeet         hot
Singh   3       Tinki           Handome

then to take all Singh and Prince(which is $1's value) into a single row we will use the code as follows and get the output as follows.

Code:
awk  '{a[$1]=a[$1]?a[$1]" "$3:$3}END{for (i in a) print i,a[i]}' test35
Prince Gurmeet
Singh Ravinder Tinki

Hope this helps.

Thanks,
R. Singh
This User Gave Thanks to RavinderSingh13 For This Post:
# 4  
Old 10-30-2014
Quote:
Originally Posted by RudiC
That's what they call "conditional assignment", it's using "?" and ":" to separate the TRUE and FALSE branch:
Code:
a[$1]=      assignment target
a[$1]       logical condition (empty or 0: FALSE; any other value: TRUE)
?           starts TRUE branch
a[$1]" "$3  concatenation of two strings
:           starts FALSE branch
$3          single simple string

man awk is your friend!
Thanks RudiC,

the clear of your explaination likes crystal ball.

Smilie

---------- Post updated at 12:18 PM ---------- Previous update was at 10:06 AM ----------

Quote:
Originally Posted by RavinderSingh13
Hello Ken6503,

Following is the explaination.

a[$1]=a[$1]?a[$1]" "$3:$3
It means we are creating a array whose index is value of $1 and if value of $1 is repeating in the further then we are concatinating the values of all $1 into a single index

Let's say we have a file as follows.

Code:
cat test35
Singh   1       Ravinder        cool
Prince  2       Gurmeet         hot
Singh   3       Tinki           Handome

then to take all Singh and Prince(which is $1's value) into a single row we will use the code as follows and get the output as follows.

Code:
awk  '{a[$1]=a[$1]?a[$1]" "$3:$3}END{for (i in a) print i,a[i]}' test35
Prince Gurmeet
Singh Ravinder Tinki

Hope this helps.

Thanks,
R. Singh
Thanks for your explaination R. Singh.
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. UNIX for Beginners Questions & Answers

If condition on awk

Hi All, Would you guys help me? I have a file that consists of several unstructured fields. in this file I will take the code field and count_berry field. but the position of the count_berry field is always changing.the column for code is always structured, which is found in column 6 I have... (4 Replies)
Discussion started by: kivale
4 Replies

2. Shell Programming and Scripting

Using like operator in awk if condition

Hello All, I have developed a script which selects a particular filed from a file ,trims it,searches for a particular pattern and then mail it when found. cat test_file.txt |sed -n '5,$p'|sed -e 's/ //g'|awk -F'|' '{if ($4 !="Alive") print $1,$2,$3,$4}' >> proc_not_alive.txt It is... (4 Replies)
Discussion started by: karthik adiga
4 Replies

3. Shell Programming and Scripting

If Condition in awk

Hi All, I have the below Input: 1 700 1200 400 1300 2 2000 1000 2000 1500 600 3 1400 200 1000 1000 1200 4 1300 500 600 200 I want to modify the field 5 and field 4 as below. If value in field 5 is null then value of field 4 should be in field 5. and then the value of... (12 Replies)
Discussion started by: am24
12 Replies

4. UNIX for Dummies Questions & Answers

awk - if else condition

Need help in awk command. Need to check 4th column of a file, if it is CAR then awk should print as is and if 4th column is not present, awk should print BIKE Input File content : 1,abc,55,CAR 3,bb,dd,CAR 5,ddd,tttt 8,ee,55 --------------------- Out put will look like: 1,abc,55,CAR... (6 Replies)
Discussion started by: vegasluxor
6 Replies

5. Shell Programming and Scripting

awk - Division with condition

Hi Friends, I have an input file like this cat input chr1 100 200 1 2 chr1 120 130 na 1 chr1 140 160 1 na chr1 170 180 na na chr1 190 220 0 0 chr1 220 230 nd 1 chr2 330 400 1 nd chr2 410 450 nd nd chr3 500 700 1 1 I want to calculate the division of 4th and 5th columns. But, if... (3 Replies)
Discussion started by: jacobs.smith
3 Replies

6. Shell Programming and Scripting

HELP with AWK one-liner. Need to employ an If condition inside AWK to check for array variable ?

Hello experts, I'm stuck with this script for three days now. Here's what i need. I need to split a large delimited (,) file into 2 files based on the value present in the last field. Samp: Something.csv bca,adc,asdf,123,12C bca,adc,asdf,123,13C def,adc,asdf,123,12A I need this split... (6 Replies)
Discussion started by: shell_boy23
6 Replies

7. Shell Programming and Scripting

awk if condition help

Hi, I need little help with awk's if condition statement. I have following code: $ ssh myRemotehost 'ps ww -fu tomcat ' | awk ' { if ($1 == "tomcat") print "tomcat (pid " $2 ") is running... "; else print "tomcat stopped or dead" }' Prints: tomcat stopped or dead tomcat (pid 12345) is... (6 Replies)
Discussion started by: davidtd
6 Replies

8. Shell Programming and Scripting

awk with multiple condition

Hi Guys, I just wanted to print all the lines execpt 1st and 3rd line. For that i wrote a awk command, awk 'NR != 1 || NR != 3 {print $0}' c.out the command is working if i give an equal to instead of not equal to. In the case of not equal to, it gives me the entire file. Can you... (18 Replies)
Discussion started by: mac4rfree
18 Replies

9. Shell Programming and Scripting

Problem with IF condition in awk

Hi all; I'm stuck with this simple awk script,i need to group the lines which the position of 28 length 3 that contains "688" into 1 group and other than "688" into another group. My problem is the script only read other than "688" and ignores the lines which contains "688". The file look... (2 Replies)
Discussion started by: ashikin_8119
2 Replies

10. Shell Programming and Scripting

awk and condition help

Hi... i just want to write a script for the follwing command "display status" and the normal output is... AN100> display status 12.13.2006 12:03:25 AN-2000-1 CC NOT PRESENT 16.50.80.49 status: Status for PACKET GLI A in the TOP / LEFT shelf of frame 0: status: The current active LAN is... (5 Replies)
Discussion started by: gini
5 Replies
Login or Register to Ask a Question