Login or Register to Ask a Question and Join Our Community


UNIX for Beginners Questions & Answers

(g)awk conditional substitution issues when attempting to delete character

Login to Discuss or Reply to this Discussion in Our Community

 
Thread Tools Search this Thread
Top Forums UNIX for Beginners Questions & Answers (g)awk conditional substitution issues when attempting to delete character
# 1  
Old 11-14-2016
(g)awk conditional substitution issues when attempting to delete character
A portion of my input is as follows:

Code:
 1087  IKON01,49 A WA-                                 -1 .       -1 .           0 W               WA-                                 -1 .        -1 .         0 .     -1 .        -1 -1 -1 -1 -1 -1 W
 1088  IKON01,49 A J.@QU80MW.                           2 !J.@!    0 .           0 QWM[            QUM                                  7 [W.       0 .         0 .      0 .         0 11  3  3  2 -1 JQMW
 1089  IKON01,49 A K.@L&                               -1 .       -1 .          -6 KL/             K.@L                                -1 .         1 /         0 .      0 .        -1 -1 -1  1  2  1 KL

I would like the following desired output:

Code:
 1087  IKON01,49 A WA-                                 -1 .       -1 .           0 W               WA-                                 -1 .        -1 .         0 .     -1 .        -1 -1 -1 -1 -1 -1 W
 1088  IKON01,49 A J.@QU80MW.                           2 !J.@!    0 .           0 QM[             QUM                                  7 [W.       0 .         0 .      0 .         0 11  3  3  2 -1 JQMW
 1089  IKON01,49 A K.@L&                               -1 .       -1 .          -6 KL/             K.@L                                -1 .         1 /         0 .      0 .        -1 -1 -1  1  2  1 KL

In essence, I would like to delete every W in field $9 while preserving the original, pre-substitution formatting, given the following regex condition:

Code:
if($9 ~/^.W[^H]=*\[$/)

However, I would want the formatting of the file to be preserved. I realize this has been dealt with in previous posts and I know how to use
Code:
printf

and/or
Code:
FIELDWIDTH

(with gawk), but since my file is 61 fields long (NF==61; I've only presented a portion here), this is tremendously cumbersome and messy. In addition, I do not know every fieldwidth and so would like to avoid figuring this out to reformat the file.

I've had a similar issue in the past, and RudiC helped me via a very nifty trick taking advantage of NF being recomputed when there is an assignment to $0. Thus, I attempted the following:

Code:
gawk '$9 ~/^.W[^H]=*\[$/{X=$9; sub(/W/,"",X); sub ($9, X, $0)}' file.txt

This time however, it seems as those when doing the field substitution, the operation is aborted because of the non-escaped meta-character "[" that is in my data. This produces the following error in field 9 of a different line:

Code:
fatal: Invalid regular expression: /BW>[/

In light of this, I've also attempted:

Code:
gawk '{if($9 ~/^.W[^H]=*\[$/); sub(/W/,"",$9); print}' file.txt

Not only does this ruin the formatting of the file, but it is also matching lines I wouldn't expect it to such as:

Code:
1  IKON01,01 A W:-                                 -1 .       -1 .           0 W               W:-                                 -1 .        -1 .         0 .     -1 .        -1 -1 -1 -1 -1 -1 W

Thank you so much in advance for helping me through this quagmire.

---------- Post updated at 11:00 AM ---------- Previous update was at 10:49 AM ----------

This is probably fairly obvious, but I should say that in my data examples from my post, the numbers on the far left are line numbers and not $1.

Thank you.
# 2  
Old 11-14-2016
This seems to work for me:
Code:
awk '$9 ~ "^.W[^H]=*\[$" {X=$9; sub(/W/, "", X); sub ($9 "[]", X " ", $0)} 1' file
IKON01,49 A WA-                                 -1 .       -1 .           0 W               WA-                                 -1 .        -1 .         0 .     -1 .        -1 -1 -1 -1 -1 -1 W
IKON01,49 A J.@QU80MW.                           2 !J.@!    0 .           0 QM[             QUM                                  7 [W.       0 .         0 .      0 .         0 11  3  3  2 -1 JQMW
IKON01,49 A K.@L&                               -1 .       -1 .          -6 KL/             K.@L                                -1 .         1 /         0 .      0 .        -1 -1 -1  1  2  1 KL


We're making the field ending "[" part of a "bracket expression" (c.f. man regex) by treating itself as the opening bracket, adding the char (the "[") and the closing bracket as char constants in the second sub statement. We need to add a space when substituting $9 to maintain the filed length and thus the $0 formatting.
These 2 Users Gave Thanks to RudiC For This Post:
jim mcnamara jvoot
# 3  
Old 11-14-2016
Thanks so much for this RudiC.

With your current line of code, the conditional, viz.,

Code:
$9 ~ "^.W[^H]=*\[$"

threw up the error code

Code:
gawk: cmd. line:1: warning: escape sequence `\[' treated as plain `['
gawk: cmd. line:1: (FILENAME=Kings.qdf FNR=1) fatal: Unmatched [, [^, [:, [., or [=: /^.W[^H]=*[$/

When I changed it to a string constant, i.e.,

Code:
$9 ~ /^.W[^H]=*\[$/

it did the trick!

I cannot thank you enough for this and look forward to studying this to see how you got it to work.
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Conditional delete -- New glitch

Hi Please dont consider this as duplicated post.. I am using below pattern to find delete files to bringdown disc size.. however how i can make sure ist going to correct folder and searching for files... while print "echo rm " LastFile correctly print files names for deletion, but when i... (7 Replies)
Discussion started by: onenessboy
7 Replies

2. Shell Programming and Scripting

Conditional delete

Hi Friends, I have somefiles like 20180720_1812.tar.gz 20180720_1912.tar.gz 20180720_2012.tar.gz 20180720_2112.tar.gz 20180721_0012.tar.gz 20180721_0112.tar.gz 20180721_0212.tar.gz 20180721_0312.tar.gz in a directory and so on..these files gets created every 3 hours where as... (28 Replies)
Discussion started by: onenessboy
28 Replies

3. UNIX for Beginners Questions & Answers

Bad substitution issues.. but why?

i am trying to prepare a train and test dataset, for which i need to randomly split the data into corresponding folders (train,test).. I began on a simple script, but seem to get som weird error messages, that i cannot make sense of?.. what am I doing wrong? #!/bin/bash RED='\033] then... (13 Replies)
Discussion started by: kidi
13 Replies

4. Shell Programming and Scripting

How to delete a character using sed and or awk?

Hi, 1/ i have file test.txt 1 Jul 28 08:35:29 2014-07-28 Root::UserA 1 Jul 28 08:36:44 2014-07-28 Root::UserB i want to delete the seconds of the file, and the Root:: and the output will be: 1 Jul 28 08:35 2014-07-28 UserA 1 Jul 28 08:36 2014-07-28 UserB 2/i have another file test2.txt:... (8 Replies)
Discussion started by: fxsme
8 Replies

5. Shell Programming and Scripting

sed or awk delete character in the lines before and after the matching line

Sample file: This is line one, this is another line, this is the PRIMARY INDEX line l ; This is another line The command should find the line with “PRIMARY INDEX” and remove the last character from the line preceding it (in this case , comma) and remove the first character from the line... (5 Replies)
Discussion started by: KC_Rules
5 Replies

6. Shell Programming and Scripting

any savant ? using AWK/SED to remove newline character between two strings : conditional removal

I'd like to remove (do a pattern or precise replacement - this I can handle in SED using Regex ) ---AFTER THE 1ST Occurrence ( i.e. on the 2nd occurrence - from the 2nd to fourth occurance ) of a specific string : type 1 -- After the 1st occurrence of 1 string1 till the 1st occurrence of... (4 Replies)
Discussion started by: sieger007
4 Replies

7. Shell Programming and Scripting

KSH: substitution character, AWK or SED?

Hi Gurus, I am working with a korn shell script. I should replace in a very great file the character ";" with a space. Example: 2750;~ 2734;~ 2778;~ 2751;~ 2751;~ 2752;~ what the fastest method is? Sed? Awk? Speed is dead main point, Seen the dimensions of the files Thanks (6 Replies)
Discussion started by: GERMANICO
6 Replies

8. Shell Programming and Scripting

Delete character in determinate position with sed/awk

Hello. I'm trying to delete one character in determinate position. Example: qwEtsdf123Ecv34 <delete character in positión 3> Result: qwtsdf123Ecv34 Plase, help me. Thanks (4 Replies)
Discussion started by: maria_florencia
4 Replies

9. Shell Programming and Scripting

Sed character substitution

Hi I have to replace in around 60 files a word an replcae it by another Suppose all the files have a word intelligent i want to replace it by idiot I am planning to use sed for executing this job sed 's/\intelligent/idiot/g' I plan to have a file (test.txt) which contains... (1 Reply)
Discussion started by: ultimatix
1 Replies

10. Shell Programming and Scripting

character substitution

Hi , I have a problem , I need to devlope a script where in the user inputs file name , line number , and character position , and a substitution variable , the character at that character position should be substituted by the substitution value for ex say i have a file abc.txt which... (3 Replies)
Discussion started by: viv1
3 Replies
Login or Register to Ask a Question