Grep command to count characters

Shell Programming and Scripting
1

I have a file that I need to count the number of "Y"s in the file, but just the "Y"s that fall between certain columns. Like:

file1:

1234567890123456789012345
BBBBBBYBBBBYBBYBBYBBYBBB

I want to count the 'Y's between 17 and 21 = 2 "Y"s

Thanks

2

Try this:

awk '{
  s=substr($0,17,5)
  n+=gsub("Y","",s)
}
END{print n}
' file
3 
$ cat input-file
1234567890123456789012345
BBBBBBYBBBBYBBYBBYBBYBBB
$ sed 's/^.\{17\}\(.\)\(.\)\(.\)\(.\).*$/\1\n\2\n\3\n\4/' input-file  | grep -c 'Y'
2
4

thegeek,

grep -c gives the count of the lines that contain the pattern, not the numbers of the pattern in a line.

Regards

5

(thegeek is outputting characters 17-21 with a newline after each character then counting the number of lines containing a letter "Y" ). Ingenious.

6 
>cat they.txt
1234567890123456789012345
BBBBBBYBBBBYBBYBBYBBYBBBB
BBBBBBYBBBBYBBYBBBBBYBBBB
BBBBBBYBBBBYBBYBYBBBBBBBB

>cut -c17-21 they.txt | sed "s/Y/Y\n/" | grep "Y" | wc -l
4
>cut -c17-21 they.txt | sed "s/Y/Y\n/" | grep "Y" -c
4
7

Just for the fun of it, another similar approach but using "fold" to break each character in each line into a separate line.

cut -c17-21 filename|fold -w 1| grep "Y"|wc -l
8

But it doesn't give the desired output:

$ cat file
1234567890123456789012345
BBBBBBYBBBBYBBYBBYBBYBBBB
BBBBBBYBBBBYBBYBBBBBYBBBB
BBBBBBYBBBBYBBYBYBBBBBBBB
$ sed 's/^.\{17\}\(.\)\(.\)\(.\)\(.\).*$/\1\n\2\n\3\n\4/' file|grep -c 'Y'
3
9

I wouldn't describe it as "ingenious" by any means, but it might work - on Linux at least - even if it does only takes characters 18 to 21 :slight_smile:

10

It is not because of grep. It is because of the characters which i have selected.

It should work now,

sed 's/^.\{16\}\(.\)\(.\)\(.\)\(.\)\(.\).*$/\1\n\2\n\3\n\4\n\5/' file | grep -c 'Y'

Selected from the character 17 to 21 as expected.

11

Right! Also with fold:

sed 's/^.\{16\}\(.\{5\}\).*$/\1/' a |fold -w 1 |grep -c 'Y'

methyl solution without the wc command is shorter:

cut -c17-21 filename|fold -w 1| grep -c 'Y'
12

Thanks everyone for your suggestions... all of them worked

13

People, people, people. Can we please stop the process forking insanity? There's only one sane way to approach this problem:

$ cat ydata
1234567890123456789012345
BBBBBBYBBBBYBBYBBYBBYBBBB
BBBBBBYBBBBYBBYBBBBBYBBBB
BBBBBBYBBBBYBBYBYBBBBBBBB

$ i=0; IFS=Y; while read x; do set ${x:16:5}.; ((i+=$#-1)); done < ydata; echo $i
4

:wink:

Cheers,
Alister