Login or Register to Ask a Question and Join Our Community


Shell Programming and Scripting

awk - loop from a to z

Login to Discuss or Reply to this Discussion in Our Community

 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting awk - loop from a to z
# 1  
Old 04-18-2011
Lightbulb awk - loop from a to z
Hello,

I was wondering if it is possible to do a loop on letters rather than numbers with awk (gawk).

Basically I used to do:
Code:
echo "nothing" | gawk '{for(i=1;i<11;i++)print i}'

But I would like to do something like that (which obviously does not work):
Code:
echo "nothing" | gawk '{for(i in a..z)print i}'

Any suggestion how to loop on the alphabet?

Thanks!

EDIT: At least I would need to be able to increment on the alphabet...
# 2  
Old 04-18-2011
I don't think plain awk has anything to turn an int into a char, but how about:
Code:
echo | awk 'BEGIN {  split("ABCDEFGHIJKLMNOPQRSTUVWXYZ", A, ""); }
{ for(N=1; N<=26; N++) printf("A[%d]=%d\n", N, A[N]); }'

Last edited by Corona688; 04-18-2011 at 02:44 PM..
# 3  
Old 04-18-2011
Quote:
Originally Posted by Corona688
I don't think plain awk has anything to turn an int into a char
You can use the %c format specifier. The following prints the lowercase alphabet (one letter per line):
Code:
awk 'BEGIN { for (i=97; i<123; i++) printf("%c\n", i) }'

Regards,
Alister
This User Gave Thanks to alister For This Post:
Corona688
# 4  
Old 04-18-2011
Code:
 echo {a..z} |xargs -n1

This User Gave Thanks to yinyuemi For This Post:
QAlan
# 5  
Old 04-18-2011
Code:
echo "nothing" | [g]awk '{gsub(""," ");for(i=1;i<=NF;i++) print $i}'

# 6  
Old 04-18-2011
Thanks!

All the solutions proposed work fine.
For my use, Alister's is the most convenient (compact and self-contained).
# 7  
Old 04-18-2011
Code:
for i in {a..z} ; do  echo $i; done

Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. UNIX for Beginners Questions & Answers

awk !seen[$]++ in else loop

Hi all, I was searching the net for a solution for my problem... unfortunately nothing so far. I want to sort on more than on column tab delimited file and keep the line if in the column I sort there is no value, but for those who have a value I want them only unique. I have tried the... (5 Replies)
Discussion started by: ksenia
5 Replies

2. UNIX for Beginners Questions & Answers

awk with For loop

Hi My Requirement is to take the sum of each column below is the input file. 1 2 3 4 1 2 3 4 1 2 3 4 Initial i was using below command to achieve my desired result. however this was adding the row and not column. i am not able understand why this is happening awk... (1 Reply)
Discussion started by: scriptor
1 Replies

3. Shell Programming and Scripting

Using awk within a for loop

Hello, I currently have managed to get an awk function working inside a for loop that allows me to combine two files based on their headings but what I have not been able to do is print the output to files with variable names. awk ' NR==FNR {a=$0; next} /^>/ {$0 = $0" "a;} ... (2 Replies)
Discussion started by: Allie_gastrator
2 Replies

4. Shell Programming and Scripting

awk programming -Passing variable to awk for loop

Hi All, I am new to AWK programming. I have the following for loop in my awk program. cat printhtml.awk: BEGIN -------- <some code here> END{ ----------<some code here> for(N=0; N<H; N++) { for(M=5; M<D; M++) print "\t" D ""; } ----- } ... (2 Replies)
Discussion started by: ctrld
2 Replies

5. Shell Programming and Scripting

awk loop using array:wish to store array values from loop for use outside loop

Here's my code: awk -F '' 'NR==FNR { if (/time/ && $5>10) A=$2" "$3":"$4":"($5-01) else if (/time/ && $5<01) A=$2" "$3":"$4-01":"(59-$5) else if (/time/ && $5<=10) A=$2" "$3":"$4":0"($5-01) else if (/close/) { B=0 n1=n2; ... (2 Replies)
Discussion started by: klane
2 Replies

6. Shell Programming and Scripting

awk loop and using shell in awk

Hi, everyone! I have a file, when I print its $1 out it show several strings like this: AABBCC AEFJKLFG FALEF FAIWEHF What I want to do is that, after output of each record, search the string in all files in the same folder, print out the record and file name. This is what I want... (4 Replies)
Discussion started by: xshang
4 Replies

7. Shell Programming and Scripting

Comparison and editing of files using awk.(And also a possible bug in awk for loop?)

I have two files which I would like to compare and then manipulate in a way. File1: pictures.txt 1.1 1.3 dance.txt 1.2 1.4 treehouse.txt 1.3 1.5 File2: pictures.txt 1.5 ref2313 1.4 ref2345 1.3 ref5432 1.2 ref4244 dance.txt 1.6 ref2342 1.5 ref2352 1.4 ref0695 1.3 ref5738 1.2... (1 Reply)
Discussion started by: linuxkid
1 Replies

8. Shell Programming and Scripting

awk for-loop and NR

Hey, I know this is a stupid question, but it doesn't work. I have a file with 10 lines and I want to pipe the content to awk and then print line 1 til 2 into another file and then line 3-4 ... So my script looks like that, but doesn't work: cat grid_ill.pts | awk '{ for (NR=1;NR<3;NR++)... (8 Replies)
Discussion started by: ergy1983
8 Replies

9. UNIX for Dummies Questions & Answers

for loop in awk?

I am new to unix and have pieced together two scripts that work independently. The first checks all the filesystems and reports which are running low on space. df -m | awk 'int($4) > 75 { print $1 " has only " $3 "mb free from a total of " $2 ", this filesystem is " $4 " full! \n" }... (1 Reply)
Discussion started by: Bdawk
1 Replies

10. Shell Programming and Scripting

Using AWK in a for loop

Hello, I am trying to use AWK to print only the first field of numerous text files, and then overwrite these files. They are of the format 1*2,3,4,5. I have tried the following code (using tcsh): foreach f (file1 file2 file3) cat $f | awk -F'*' '{print $1}' > $f end However, I get very... (4 Replies)
Discussion started by: Jahn
4 Replies
Login or Register to Ask a Question