How to remove duplicate characters when combining two strings in shell script

Question

I have 2 strings and I want to combine them and remove duplicates.

Example:

str1=/home/username
str2=/home/username/project
str3=$str1+$str2

Result:

echo $str3
>> /home/username/project

How do i provided it like str3?

My thought is, the premise of your question is highly likely to be wrong. The fact that you want to do this means you probably already have gone off track. Then again, who knows, requirements are many and varied. — xpusostomos
– xpusostomos, Commented Jul 20, 2022 at 8:43

tripleee · Accepted Answer · 2022-07-20 08:27:31Z

2

There is no built-in facility for this. If you know that str2 may or may not contain str1 as a prefix, you can exclude it with a parameter expansion:

str3=$str1${str2#"$str1"}

The quotes are necessary to guard against shell metacharacters in the pattern; for example, ${foo#*} removes everything from foo whereas ${foo#"*"} only removes a literal asterisk if present.

answered Jul 20, 2022 at 8:27

tripleee

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2 Comments

xpusostomos Over a year ago

Does this work if str1 may or may not contain str2, or does it only work if str2 may or may not contain str1? The original poster is asking a poor question, but taken literally it has to do both.

tripleee Over a year ago

This is only for exactly the case in the first paragraph.

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