Question

I have a text file (FILE_A.txt) with this content:

Content1
Content2
Content3

And other text file (FILE_B.txt) with this content:

A[#]
B[#]
C[#]

I would like to combine FILE_A.txt and FILE_B.txt in other file (FILE_C.txt) in this way:

A[Content1]
B[Content2]
C[Content3]

How could I make this using bash shell in linux (sed, cut, grep, etc)?

Answer 1

Here we go.

# awk 'NR==FNR{a[NR]=$0;next;} sub(/#/,a[FNR])' FILE_A.txt FILE_B.txt
A[Content1]
B[Content2]
C[Content3]

How does this work?

• NR==FNR – causes the following statements to be run if the record number matches the FILE record number – that is, we are currently reading only the firs tfile.
• {a[NR]=$0;next;} – Store values from the first file in an array.
• sub(/#/,a[FNR]) – Once we’re in the second file, substitute # for the matching value stored from the first file. Note that this isn’t inside curly brackets, so it’s being evaluated as a condition. If the sub() statement succeeds, the current line is printed.