Comparing string in 2 files and appending the data in shell script

Question

I have 2 files 1.txt and 2.txt

1.txt contains below details

user = 10
user2 = 20
user3 = 30

2.txt contains below details

user = 25MB
user2 = 30MB

I need to compare both the files if the string matches in the files it should append the data from 1st file and if it does not match it should append 0 in shell script

Desired output

user = 10 25MB
user2 = 20 30MB
user3 = 30 0MB

I am using the command:

awk 'FNR==NR{a[$1$2];next}!($1$2 in a)' 1.txt 2.txt

but not getting the desired output. I am new to shell scripting and looking for full implementation help.

Could you please help me with the syntax and implementation?

Tom Fenech · Accepted Answer · 2016-01-21 10:17:15Z

1

You could use something like this:

$ awk 'NR == FNR { a[$1] = $3; next } 
       { printf "%s = %s %s\n", $1, $3, ($1 in a ? a[$1] : "0MB") }' 2.txt 1.txt
user = 10 25MB
user2 = 20 30MB
user3 = 30 0MB

I chose to read the files in the opposite order, 2.txt, then 1.txt. The keys and values from 2.txt are stored in the array a. For each line in 1.txt, the value in the array corresponding to the key is used if present.

answered Jan 21, 2016 at 10:17

Tom Fenech

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