Linux – How to join 2 files in Linux

How to join 2 files in Linux… here is a solution to the problem.

How to join 2 files in Linux

I have 2 files file_A and file_B. File file_A contains the file name, followed by a space followed by a line of code. This line of code can contain characters of random types, such as spaces, :, and so on. It looks like this. Notice that the lines of code in the file are not surrounded by (). This is for illustrative purposes only.

bash$ cat file_A

file_name1 (code line a)
file_name1 (code line b)
file_name2 (code line c)
file_name2 (code line d)
file_name2 (code line e)

File file_B contains frequencies in file_name and file_A

bash$cat file_B

file_name1 2
file_name2 3

I want the output to be: (frequency,file_name,code_line).

2 file_name1 (code line a)
2 file_name1 (code line b)
3 file_name2 (code line c)
3 file_name2 (code line d)
3 file_name2 (code line e)

bash$ join -1 1 -2 1 file_B file_A > file_C

I get

file_C as (I get the join field as the first field).

file_name1 2 (code line a)
file_name1 2 (code line b)
file_name2 3 (code line c)
file_name2 3 (code line d)
file_name2 3 (code line e)

How do I get the frequency field in the first field?


know that with join I can use the -o format and mention the fields and order I want in the output. But how do I say put everything in a line of code (it can contain anything, so there are no separators).



join file_B file_A | awk '{t=$1; $1=$2; $2=t; print}' > file_C

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