Shell Programming and Scripting

Hi ,

I am greping a keyword in all sql files in Solaris and Linux.

Solaris

Code:

 
bash-3.00$  time grep -iwc BEN_STARTUP_LERS_TL084701_WHO *.sql
Load__v20130719-prod.sql:0
Load__v20130719-prod.sql:0
Load__v20130719-prod.sql:0
Load__v20130719-prod.sql:0
Load__v20130719-prod.sql:0
Load__v20130719-prod.sql:0
real    0m0.640s
user    0m0.564s
sys     0m0.077s

Linux

Code:

 
[Sql]$ time grep -iwc BEN_STARTUP_LERS_TL084701_WHO *.sql
Load__v20130719-prod.sql:0
Load__v20130719-prod.sql:0
Load__v20130719-prod.sql:0
Load__v20130719-prod.sql:0
Load__v20130719-prod.sql:0
real    0m2.518s
user    0m2.499s
sys     0m0.013s

If you see in solaris it is taking less than one second where as in linux it is taking more than 2 sec to execute the same command.

Infact my aim is to reduce the time taken by this command as less as possible may be a littile fraction of a second because i have around 50k keywords to search..

Can anyone please advice how to reduce the execution time.

if you are trying to search for fixed strings, you can use fgrep which is more faster than grep.
fgrep (grep -F in linux) is fixed or fast grep and behaves as grep but does not recognise any regular expression metacharacters as being special.

Ensure a non-UTF locale

Code:

LC_ALL=C grep ...

OS is a factor, as is filesystem, amount of free memory (esp. for Linux's read ahead ), I recommend faster disk storage or flash drives if you want to read files faster
grep is a pretty optimised command as it is...

Edit: Actually, on the locale issue, make sure "LC_COLLATE=Posix" if you're using ranges in grep.

Case matters in locale names. The POSIX Locale is all caps. Furthermore, on systems that conform to the IEEE's and ISO's POSIX Standards or The Open Group's Single UNIX Specifications, the C Locale and the POSIX Locale are identical. So LC_COLLATE=C and LC_COLLATE=POSIX have exactly the same effect. LC_COLLATE=Posix might have the same effect, might yield an error, or might be a completely different locale on some systems; but it has no defined meaning in the standards.

On systems that conform to the C standard but neither the POSIX Standards nor the Single UNIX Specifications, the requirements for the C Locale are not as stringent and there is no definition for, nor any requirement that there even be, a POSIX Locale.