UNIX for Beginners Questions & Answers

Hello,

My OS is Windows 10 and I am using Cygwin.

The content of file 1 is:
XXX string1

The content of file 2 is
4.156
2.312
3.527
1.687
etc....

I need to replace string 1 in file 1 by the content of line n in file 2.

So the expected output is e.g.:
XXX 3.527 (for n = 3)

I have the following script:

Code:

sed "s/string1/$(cat file2.txt)/" file1.txt > file3.txt

How can I adapt it to get the replacement of string 1 by the nth line of file 2?

Thanks in advance.

Hello supernono06,

Could you please try following and let me know if this helps.

Code:

awk -v n=3 'FNR==NR{a[FNR]=$0;next} {sub("string1",a[n])} 1' file2  file1

OR in case you directly want to assign value from file2 to file1 on 2nd field of file1 then following may help you.

Code:

 awk -v n=3 'FNR==NR{a[FNR]=$0;next} {$2=a[n]} 1' file2  file1

Thanks,
R. Singh

Hello RavinderSingh13,

It works perfectly, many thanks.

If n is large, is there a way to use a loop to do the following:

Code:

 
awk -v n=1 'FNR==NR{a[FNR]=$0;next} {sub("string1",a[n])} 1' file2  file1
awk -v n=2 'FNR==NR{a[FNR]=$0;next} {sub("string2",a[n])} 1' file2  file1
awk -v n=3 'FNR==NR{a[FNR]=$0;next} {sub("string3",a[n])} 1' file2  file1
etc.…

Thanks.

Hello supernono06,

You could HIT THANKS button left most corner of any post if you feel it helped you . Now coming to your problem, no need to use a loop for this. There could be 2 situations for this.

1st: To substitute all the string keywords in file1 in that case following may help you.

Code:

awk  'FNR==NR{a[FNR]=$0;next} {sub("string1",a[FNR])} 1' file2  file1

Above will change them as per file2's line number so let's say string keywords comes on 1st, 3rd line of file1 so it will substitute string keyword with respective line's value from file2 in file1.

2nd: In case you want to give multiple values of line numbers which you want to change in file1, then following may help you.

Code:

awk -v n="1,4"  'BEGIN{num=split(n,array,",")} FNR==NR{a[FNR]=$0;next} /string/{count=count==num?1:++count;gsub("string",a[array[count++]])} 1' file2  file1

So in this case line number(s) 1st and 4th from file2's value will substituted on file1's keyword string. Also it will not bother line number on file1 side(asap a string (string) comes it will substitute it).

Thanks,
R. Singh

Hello RavinderSingh13,

Thanks, but it is not doing what I need, I will explain it better.

The file 1 content is:
…..
XXX string1
….
YYY string2
...
ZZZ string3
...
AAA string4
….
The file 2 content is:
3.333
4.251
1.121
5.456

The expected output is:
...
XXX 3.333
...
YYY 4.251
…
ZZZ 1.121
...
AAA 5.456
…

Thanks in advance.

Supernono06

Hello supernono06,

Could you please try following and let me know if this helps you.

Code:

 awk 'FNR==NR{a[FNR]=$0;next} {print $1,a[FNR]}'  Input_file2  Input_file1

Thanks,
R. Singh

Hello RavinderSingh13,

Thanks but it is not working. With this script, the replacement takes place in the second field of the four 4th lines of the files, and all other 2nd fields of the remaining lines are removed.

I need to mention that there are lines above and below the strings I need to replace.

Supernono06