If you don't care about order:

$ sort -u tt.txt
123
133
3243
a
b
c
[download]

If you do:

$ perl -ne'$s{$_}++||print' tt.txt
a
b
c
123
3243
133
[download]

Same, but one char shorter: (requires Perl 5.10 or higher)

$ perl -nlE'$s{$_}++||say' tt.txt
a
b
c
123
3243
133
[download]

Thanks!

Now I know }{ and understand toolic's one line.But autovivification in your code confused me, does it mean returning FALSE when created autovivification? Any document for my reference?





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I am trying to improve my English skills, if you see a mistake please feel free to reply or /msg me a correction

Fetching a non-existent hash element returns undef. Is that what you meant? There's no autovivification. The hash elements are created when ++ assigns a value to them.

perl -ne '$h{$_}++}{print for keys%h' tt.txt
[download]

Update: not to mention sort...

sort -u tt.txt
[download]

Obfuscated code for me, absolutely! what does }{ mean? help! ;)




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I am trying to improve my English skills, if you see a mistake please feel free to reply or /msg me a correction

What comes after ends up outside the -n loop.

$ perl -MO=Deparse -ne'f()'
LINE: while (defined($_ = <ARGV>)) {
    f();
}
-e syntax OK

$ perl -MO=Deparse -ne'f() }{ g()'
LINE: while (defined($_ = <ARGV>)) {
    f();
}
{
    g();
}
-e syntax OK
[download]