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Old 02-04-2012, 04:11 PM   #1
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Registered: Feb 2012
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Post Remove duplicate lines alias

Hello all,
This is a great forum and my first time posting on it.
I would like to have a bash alias like this
alias dup="{ rm \$* && awk '!(\$0 in t){t[\$0];print}' > \$*; } < \$*"
which would remove duplicate lines from a file without sorting it first. I have tried many different combinations, but always seem to end with this error.
bash: syntax error near unexpected token `authorized_keys'
Is there a way to have an alias which you type in
dup authorized_keys
and it successfully removes the duplicate lines without sorting?
I have also replaced
awk '!(\$0 in t){t[\$0];print}'
perl -ne 'print unless $a{$_}++'
and there was no change. Any ideas? Thanks!
Old 02-04-2012, 04:39 PM   #2
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For the perl onliner, try:
alias dup="perl -i -ne 'print unless \$a{\$_}++' \$*"
1 members found this post helpful.
Old 02-05-2012, 12:37 AM   #3
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Thank you, Cedrik. The perl oneliner works perfectly!
Old 02-05-2012, 05:00 AM   #4
David the H.
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Aliases are designed generally for simple command substitutions (if the command name matches the alias, the designated string is substituted before the line is executed), and are not really appropriate for more complex commands like this. I'd recommend setting it up as a shell function instead.

	{ rm -f "$1" && awk '!( $0 in t ){ t[$0] ; print }' > "$1" ;} <"$1"
Edit: You could also simply set your command up as a stand-alone script, and either alias your command name to the script location, or just put/symlink the script somewhere in your path. I see no real reason why you have to clutter up your shell environment with a command like this.

Last edited by David the H.; 02-05-2012 at 05:21 AM. Reason: as stated


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