Login or Register to Ask a Question and Join Our Community


UNIX for Beginners Questions & Answers

Awk/bash one liner replacement for a if condition

Login to Discuss or Reply to this Discussion in Our Community

 
Thread Tools Search this Thread
Top Forums UNIX for Beginners Questions & Answers Awk/bash one liner replacement for a if condition
# 1  
Old 12-02-2019
Awk/bash one liner replacement for a if condition
Hi.

I wrote this small bash script, i want to compare second column from file1 with file2 if a pattern matches. Files are small and I am sure that pattern occurs only once. I think this can be rewritten into a awk one liner. Appreciate if someone could give me idea. Whole NR FNR confuse me Smilie
Code:
#!/bin/bash
var1=$(awk '/pattern/ { print $2 }' file1)
var2=$(awk '/pattern/ { print $2 }' file2)
if [[  "${var1}" != "${var2}" ]];then
    echo "Second column is not matching"
fi

# 2  
Old 12-02-2019
If "I am sure that pattern occurs only once" (per file, I presume), how about
Code:
if awk '/pattern/ {T[$2]++}; END {for (t in T) if (T[t] > 1) exit 1}' file[12]
  then echo "Second column is not matching"
fi

This User Gave Thanks to RudiC For This Post:
ctrld
# 3  
Old 12-02-2019
Awesome and super quick! Smilie

I just made a small adjustment for better look. Please correct me if I am wrong :

Code:
awk '/pattern/ {T[$2]++}; END {for (t in T) if (T[t] > 1){print "Second column is not matching"}}' file[12]

# 4  
Old 12-02-2019
If you are hitting memory limits, you could almost go very old-school:-
Code:
awk '/pattern/ { print $2 }' file1 | sort > $workdir/file1_col2
awk '/pattern/ { print $2 }' file2 | sort > $workdir/file2_col2
diff $workdir/file1_col2$workdir/file2_col2

Probably slow because of the disk access and if it's too big, then diff may also struggle.

Not the best, but a clunky way to be sure it will actually work. Perhaps this will give you a good basis to see what output from a better (more efficient) process should be.




Robin
# 5  
Old 12-02-2019
I am extremely sorry! I think I was late to note that I wanted reverse of what this code is doing now;

Code:
if awk '/pattern/ {T[$2]++}; END {for (t in T) if (T[t] > 1) exit 1}' file[12]
  then echo "Second column is not matching"
fi

At present it is printing when columns are matching, I needed when columns are NOT matching.
# 6  
Old 12-02-2019
Quote:
Originally Posted by ctrld
Awesome and super quick! Smilie

I just made a small adjustment for better look. Please correct me if I am wrong :

Code:
awk '/pattern/ {T[$2]++}; END {for (t in T) if (T[t] > 1){print "Second column is not matching"}}' file[12]

Fine if that suits you. I was thinking you might want to perform further shell commands in the ifbranch...






Quote:
Originally Posted by ctrld
I am extremely sorry! I think I was late to note that I wanted reverse of what this code is doing now;

Code:
if awk '/pattern/ {T[$2]++}; END {for (t in T) if (T[t] > 1) exit 1}' file[12]
  then echo "Second column is not matching"
fi

At present it is printing when columns are matching, I needed when columns are NOT matching.

Well, try if ! awk..., then. Or use the else branch...
This User Gave Thanks to RudiC For This Post:
ctrld
# 7  
Old 12-02-2019
Thank you for confirming Smilie
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. UNIX for Beginners Questions & Answers

Perl one liner in bash script not replacing hours and minutes [HH:MM]

Hi I want to replace time stamp in the following line PROCNAME.Merge.exchMon.CODE.T_QSTART 08:45 read assuming the new time stamp is 09:45 ; the line is getting replaced as below :45 read I'm trying to use the perl one liner in bash script perl -pi... (4 Replies)
Discussion started by: charlie87
4 Replies

2. Programming

Resample time series data with replacement any way to do this in awk or just bash script

I have some time series data that I need to resample or downsample at some specific time intervals. The firs column is time in decimal hours. I am tryiong to resample this data every 3 minutse. So I need a data value ever 0.05. Here is the example data and as you can see, there time slot for 0.1500... (3 Replies)
Discussion started by: malandisa
3 Replies

3. 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

4. Shell Programming and Scripting

Search & Replace regex Perl one liner to AWK one liner

Thanks for giving your time and effort to answer questions and helping newbies like me understand awk. I have a huge file, millions of lines, so perl takes quite a bit of time, I'd like to convert these perl one liners to awk. Basically I'd like all lines with ISA sandwiched between... (9 Replies)
Discussion started by: verge
9 Replies

5. Shell Programming and Scripting

Bash string replacement - how to use regex?

Hello I have a bash script where I need to do a substring replacement like this: variable2=${variable1/foo/bar} However, I only want "foo" replaced if it is at the end of the line. However, this does not work: variable2=${variable1/foo$/bar} as you can see I'm using the $ regex for... (2 Replies)
Discussion started by: Ubuntu-UK
2 Replies

6. UNIX for Dummies Questions & Answers

awk one liner

I need a one liner to" find /pattern/ print from x lines before "pattern" to y lines after "pattern" (3 Replies)
Discussion started by: kenneth.mcbride
3 Replies

7. Shell Programming and Scripting

Bash replacement to getchar

There's a replacement in bash for getchar or get functions of C and C++?Those functions read the next char avaliable in the input stream. I've tried something like: OLD_STTY=`stty -g` stty cbreak -echo look=`dd if=/dev/tty bs=1 count=1 2>/dev/null` stty $OLD_STTY But it is not working... (3 Replies)
Discussion started by: Asafe
3 Replies

8. Shell Programming and Scripting

Bash one liner to CSH

Hello all, I have a Bash command I'm using on one system that replaces text in filenames, I'ts not working on another system that uses the Csh shell. Can anyone tell me what I need to do when i run for f in *;do mv $f ${f/text1/text2};done on the CSH shell i get ""Missing }."" (7 Replies)
Discussion started by: mike171562
7 Replies

9. UNIX for Dummies Questions & Answers

Awk/Sed One liner for text replacement

Hi group, I want to replace the occurance of a particular text in a paragraph.I tried with Sed,but Sed only displays the result on the screen.How can i update the changes in the original file??? The solution should be a one liner using awk and sed. Thanks in advance. (5 Replies)
Discussion started by: bishnu.bhatta
5 Replies

10. Shell Programming and Scripting

Bad day !! test condition failed --need a one liner to do --help

Hi all this is simple but bad day for me nothing work out .. Problem is that I wan to check the argument passed to my script and accordignly exit or setup ENV variable I have a script name src_cpcp_preproc.sh i want to pass 2 argumet from command line argumet and check it in the script... (13 Replies)
Discussion started by: jambesh
13 Replies
Login or Register to Ask a Question