Add a character at a specific location within strings using Awk

Folks, in previous examples we saw how to add a prefix to strings in a file and how to add a suffix to strings in a file. In today's example, we'll see how to add a character somewhere in the middle of multiple strings in a file at the same time.

We'll use the same data as used in previous examples. Let's use a text file named Phones_unformatted.txt with the following phone numbers data :

2127841212
3458922345
7713398403
6461228847

Now we want to add a - sign after the first 3 digits to separate the area code. Notice that all phone numbers are of 10 digits. We want to add a - sign between the 3rd and 4th character.

For doing this lets use awk again :

awk '$0=substr($0,1,3) "-" substr($0,4,7)' Phones_unformatted.txt

Output :

212-7841212

345-8922345

771-3398403

646-1228847

Notice how we have used substr() function to split the entire 10 digit phone number into 2 parts. The first part is between 1-3rd character and the second part is from 4-10th character.

Similarly, lets say for e.g. we want to add the - sign twice within the string i.e once between 3rd and 4th character and the next - between 6th and 7th character. The awk code for doing this is as follows :

awk '$0=substr($0,1,3) "-" substr($0,4,3) "-" substr($0,7,4)' Phones_unformatted.txt

Output :

212-784-1212

345-892-2345

771-339-8403

646-122-8847

This way, you could append the string with the "-" character or anything like a dot "." or maybe just a whitespace " ".

awk '$0=substr($0,1,3) " " substr($0,4,3) " " substr($0,7,4)' Phones_unformatted.txt

Output :

212 784 1212

345 892 2345

771 339 8403

646 122 8847

Add suffix to strings in a file using Awk

Guys, in my previous post yesterday, we discussed how to add a prefix to strings in a file using Awk. Today lets work on the same example to add a suffix to the strings i.e append the strings with characters in the end.

We'll use the same set of phone numbers for formatting :

2127841212
3458922345
7713398403
6461228847

Let's add some characters to the these numbers in the end. How about something like " Extn : 7142". Here's the Awk code to do it below :

awk '{print $0 " Extn : 7142"}' Phones_unformatted.txt

Output :

2127841212 Extn : 7142

3458922345 Extn : 7142

7713398403 Extn : 7142

6461228847 Extn : 7142

Add a prefix to strings in a file using Awk

Suppose you have a file in Unix / Mac OS X which has phone numbers data. I mean lets say I have a text file named Phones_unformatted.txt which has some phone numbers as follows :

2127841212
3458922345
7713398403
6461228847

Now I want to format the phone numbers to have a prefix maybe like a country code +44- . something like :

+44-2127841212
+44-3458922345
+44-7713398403
+44-6461228847

If you observe I need to only append the phone number with some characters in the beginning. We can achieve the same using awk.

A simple awk code will do the trick as follows :

awk '{print "+44-" $0}' Phones_unformatted.txt

Output :

+44-2127841212

+44-3458922345

+44-7713398403

+44-6461228847

Viola!