09-07-2017
Quote:
Originally Posted by
Peu Mukherjee
Thank you all for your response
The below command has really helped in reducing the time. Would this also sort the rows or do we need to use sort after this?
It reduced time by not sorting it. That's liable to be what took the lion's share of the time.
If you need it sorted, and need it sorted faster, point
sort to a different disk for temporary space with -T /path/to/folder. Using a different disk for temp space will increase the speed your data can be read.
GNU sort also has a --parallel option, but this is not much help unless you have extraordinarily fast disks.
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look(1) General Commands Manual look(1)
NAME
look - Finds lines in a sorted list
SYNOPSIS
look [-df] [-tcharacter] string [file]
The look command prints all lines in a sorted file that begin with string.
OPTIONS
Uses dictionary order; only letters, digits, tabs, and spaces are used in comparisons. Searches without regard to case; treats uppercase
and lowercase as equivalent. Ignores character and characters following it in the search string. If you specify look -tC ABCDE, the
string ABCDE would become (in effect) AB, with CDE being ignored. This option is primarily for shell scripts, in which more than one
string is being processed.
DESCRIPTION
If no file is specified, look searches in the system word list /usr/share/dict/words, with the options -df assumed by default.
The look command uses binary search.
The -d and -f options affect comparisons as in sort.
NOTES
In order to use the -f option, you must first sort file with the sort -f command; otherwise, look displays only lowercase items.
If you do not specify -f, but specify a file (such as /usr/share/dict/words) that has been sorted with sort -f, look may not produce any
output.
EXAMPLES
To search a sorted file called sortfile for all lines that begin with the string as, enter: look as sortfile To search the system word list
for all words beginning with smi, enter: look smi
This might result in: smile smirk smith smithereens Smithfield Smithson smithy smitten
FILES
System word list.
SEE ALSO
Commands: grep(1), sort(1), spell(1)
look(1)