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Full Discussion: Statement to find if an entry exists in a file
Top Forums UNIX for Dummies Questions & Answers Statement to find if an entry exists in a file Post 302638047 by neutronscott on Wednesday 9th of May 2012 09:09:33 PM
Old 05-09-2012
What OS version and which shell? You can also try awk to replace grep.

Code:
record_file=/path/to/some/file.txt

record_exists() {
    awk -v "record=$1" 'index($0,record) {found=1;exit} END {exit !found}' "$record_file"
}

read record
if record_exists "$record"; then
  #do stuff
else
  #do other stuff
fi

edit: to be more specific about matching, if your record file is for instance delimited you can check a specific field. for instance finding a username in /etc/passwd. /etc/passwd is delimited with : and the username is the first field

Code:
user_exists() {
    awk -F: -v "user=$1" '$1 == user {found=1;exit} END {exit !found}' /etc/passwd
}

Last edited by neutronscott; 05-09-2012 at 10:15 PM..
 

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LEARN ABOUT MOJAVE

ppi::statement::unknown5.18

PPI::Statement::Unknown(3)				User Contributed Perl Documentation				PPI::Statement::Unknown(3)

NAME

       PPI::Statement::Unknown - An unknown or transient statement

INHERITANCE

	 PPI::Statement::Unknown
	 isa PPI::Statement
	     isa PPI::Node
		 isa PPI::Element

DESCRIPTION

       The "PPI::Statement::Unknown" class is used primarily during the lexing process to hold elements that are known to be statement, but for
       which the exact "type" of statement is as yet unknown, and requires further tokens in order to resolve the correct type.

       They should not exist in a fully parse valid document, and if any exists they indicate either a problem in Document, or possibly (by
       allowing it to get through unresolved) a bug in PPI::Lexer.

METHODS

       "PPI::Statement::Unknown" has no additional methods beyond the default ones provided by PPI::Statement, PPI::Node and PPI::Element.

SUPPORT

       See the support section in the main module.

AUTHOR

       Adam Kennedy <adamk@cpan.org>

COPYRIGHT

       Copyright 2001 - 2011 Adam Kennedy.

       This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

       The full text of the license can be found in the LICENSE file included with this module.

perl v5.18.2							    2011-02-25						PPI::Statement::Unknown(3)
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