linux - merge files with bash by primary key

Question

I have two files with with IP-Addresses as the primary key. File two has just a subset with different informations. I would like to add the 2nd column to the first file using bash.

file1:

192.168.1.1;hosta;aabbccddeef0
192.168.1.2;hostb;aabbccddeef1
192.168.1.3;hostc;aabbccddeef2

file2:

192.168.1.2;differentHostname;

My approach with for addr in cat file2 | cut -d; -f1; do grep -w $addr file1 ... does not work, since I cannot access the hostname from file2.

Any ideas?

Answer 1

This is what join does:

$ join -a1 -t';' <(sort file1) <(sort file2)    
192.168.1.1;hosta;aabbccddeef0
192.168.1.2;hostb,aabbccddeef1;differentHostname;
192.168.1.3;hostc,aabbccddeef2

Note: join require files in sorted order.

You can specify the order of output using the -o option:

$ join -a1 -t';' -o 1.1 1.2 2.2 1.3 <(sort file1) <(sort file2)
192.168.1.1;hosta;;aabbccddeef0
192.168.1.2;hostb;differentHostname;aabbccddeef1
192.168.1.3;hostc;;aabbccddeef2