grep exact word

publicLearner · 07-22-2015, 09:55 AM

Hi Team,
I'm stuck with a small thing of grepping file names which have exact start word, or start with a specified word.

Quote:

g="19_S22_L001_R1_001.fastq.gz"

Code:

echo $g | grep  -w "19"

This gives me no output

The reason I'm trying to grep so, is I'm dealing with ~150+ files, and I'll have files with same pattern but different starts say 1 or 19

Code:

echo $g | grep "^19"

and

Code:

echo $g | grep "^1"

will give me same results.

Linux version:

Linux version 2.6.32-504.12.2.el6.x86_64 (mockbuild@x86-027.build.eng.bos.redhat.com) (gcc version 4.4.7 20120313 (Red Hat 4.4.7-9) (GCC) ) #1 SMP Sun Feb 1 12:14:02 EST 2015

How do I overcome this barrier?

Kindly help

schneidz · 07-22-2015, 10:00 AM

underscore (_) is considered a letter; what does this yield

Code:

echo $g | grep "^19_"
echo $g | grep "^1_"

publicLearner · 07-22-2015, 10:04 AM

Quote:

Originally Posted by schneidz

underscore (_) is considered a letter; what does this yield

Code:

echo $g | grep "^19_"
echo $g | grep "^1_"

Hi schneidz,

Thanks for your prompt reply.

Code:

echo $g | grep "^19_"

This works.!

grail · 07-22-2015, 10:20 AM

I am a little confused ... you talk about finding file names but are using grep? Wouldn't you just use find?

Code:

find path -name '19*'

publicLearner · 07-22-2015, 11:33 AM

Quote:

Originally Posted by grail

I am a little confused ... you talk about finding file names but are using grep? Wouldn't you just use find?

Code:

find path -name '19*'

Hi grail,
Thanks for your attention to my query and putting awesome question.

Output from below command:

Code:

find -type f -name "1*"

shall be same as with:

Code:

find -type f -name "19*"

provided I've files present with 19 and 1 both in designated directory.

schneidz · 07-22-2015, 11:35 AM

sigh, what does this yeild:

Code:

find -type f -name "1_*"
find -type f -name "19_*"

publicLearner · 07-22-2015, 12:19 PM

Quote:

Originally Posted by schneidz

sigh, what does this yeild:

Code:

find -type f -name "1_*"
find -type f -name "19_*"

It yields correct output. Thanks.

PS: This is so embarrassing for me.

syg00 · 07-22-2015, 05:54 PM

"locate" is much less resource intensive, and supports regex - may also be an option.

grail · 07-23-2015, 03:12 AM

Don't be embarrassed ... no one here was a guru the first time they used linux