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Full Discussion: Speeding up shell script with grep
Top Forums Shell Programming and Scripting Speeding up shell script with grep Post 302994609 by Don Cragun on Saturday 25th of March 2017 06:07:42 AM
Old 03-25-2017
In addition to what bakunin suggested, you might also consider the following to more closely match the output produced by your current script...

Making the wild assumptions that:
  1. master.csv is a character separated values file with comma as the character separating fields, and
  2. the field containing the phone number in master.csv is the 1st field
how long does the following script take:
Code:
awk -v fn=1 -F',' '
FNR == NR {
	p[$fn]
	next
}
{	print "checking master for phone number", $1
	if($1 in p) {
		print $1, "already exists in master file "
		print > "unusable_numbers"
	} else {
		print $1, "looks good we can use this saving to usable_numbers"
		print > "useable_numbers"
	}
}' master.csv new

to do the same job?

If the field number in master.csv is not the 1st field, change the value assigned to the fn variable from 1 to the field number of the field containing the phone number.

If the field separators in master.csv are not commas, change the character in the -F option-argument to the desired character.
 

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LEARN ABOUT REDHAT

cut

CUT(1)									FSF								    CUT(1)

NAME

       cut - remove sections from each line of files

SYNOPSIS

       cut [OPTION]... [FILE]...

DESCRIPTION

       Print selected parts of lines from each FILE to standard output.

       Mandatory arguments to long options are mandatory for short options too.

       -b, --bytes=LIST
	      output only these bytes

       -c, --characters=LIST
	      output only these characters

       -d, --delimiter=DELIM
	      use DELIM instead of TAB for field delimiter

       -f, --fields=LIST
	      output only these fields;  also print any line that contains no delimiter character, unless the -s option is specified

       -n     with -b: don't split multibyte characters

       -s, --only-delimited
	      do not print lines not containing delimiters

       --output-delimiter=STRING
	      use STRING as the output delimiter the default is to use the input delimiter

       --help display this help and exit

       --version
	      output version information and exit

       Use one, and only one of -b, -c or -f.  Each LIST is made up of one range, or many ranges separated by commas.  Each range is one of:

       N      N'th byte, character or field, counted from 1

       N-     from N'th byte, character or field, to end of line

       N-M    from N'th to M'th (included) byte, character or field

       -M     from first to M'th (included) byte, character or field

       With no FILE, or when FILE is -, read standard input.

AUTHOR

       Written by David Ihnat, David MacKenzie, and Jim Meyering.

REPORTING BUGS

       Report bugs to <bug-coreutils@gnu.org>.

COPYRIGHT

       Copyright (C) 2002 Free Software Foundation, Inc.
       This is free software; see the source for copying conditions.  There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICU-
       LAR PURPOSE.

SEE ALSO

       The full documentation for cut is maintained as a Texinfo manual.  If the info and cut programs are properly installed at  your	site,  the
       command

	      info cut

       should give you access to the complete manual.

cut (coreutils) 4.5.3						   February 2003							    CUT(1)
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