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Full Discussion: Which cut command is more efficient?
Top Forums UNIX for Advanced & Expert Users Which cut command is more efficient? Post 302507397 by methyl on Wednesday 23rd of March 2011 06:01:56 PM
Old 03-23-2011
@Corona688
Yes, 36 cores (9x4). CPU power not an issue. Regularly running over 30,000 concurrent processes.

Bottleneck on reading large files is invariably the disc system, closely followed by the software. This is where reading moderate size files with "cat" scores over the read function in some unix utilities. I recognise that "cut" is actually one of the better ones.

For the advanced user with large data files I am not averse to using "dd" or "cpio" (or both) to read from the disc in an optimum manner.

On a single core system running ancient unix it was very important to minimise the number of concurrent processes. This is really not the case nowadays unless you happen to be running unix on a home system.

Back to the O/P.
The conventional answer is that running more processes is less efficient. On a modern large system with multiple processors (i.e. the norm) it can be more efficient to run a pipeline of multiple efficient processes than to run a single inefficient process.
The "Useless use of cat" brigade have clearly never used a modern computer where apparent inefficiencies are in fact covered by proper utilisation of the software and hardware as a team.
By applying lateral thought we can deduce that hardware design evolution is actually targetted towards making inefficient processes efficient. We can take advantage of that by tactical use of the previously-inefficent processes.

Nuff said.
Last edited by methyl; 03-23-2011 at 07:07 PM.. Reason: spellin, verbosity
 

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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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