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bashuniquedistinctkshsh

Select unique or distinct values from a list in UNIX shell script

I have a ksh script that returns a long list of values, newline separated, and I want to see only the unique/distinct values. It is possible to do this?

For example, say my output is file suffixes in a directory:

tar
gz
java
gz
java
tar
class
class

I want to see a list like:

tar
gz
java
class
Solution

  • You might want to look at the uniq and sort applications.

    ./yourscript.ksh | sort | uniq

    (FYI, yes, the sort is necessary in this command line, uniq only strips duplicate lines that are immediately after each other)

    EDIT:

    Contrary to what has been posted by Aaron Digulla in relation to uniq's commandline options:

    Given the following input:

    class
jar
jar
jar
bin
bin
java

    uniq will output all lines exactly once:

    class
jar
bin
java

    uniq -d will output all lines that appear more than once, and it will print them once:

    jar
bin

    uniq -u will output all lines that appear exactly once, and it will print them once:

    class
java