special character with grep

[Guest Vaibhav]

hi

 

I was learning about samba and I learnt that coders of SAMBA decided on its name by searching directory by using the command :-

grep -i "s.*m.*b.*" /home/dictionary/words

 

why they have used . (dot) here when there is no special character in books as . (dot) .

 

As by rules "s*m*b*" should work .

 

I also tried the command in a directory, where I added a new file sambar.dia.

using

ls | grep -i "s*m*b*" gave names of all the files or directories with s, m or b.

 

But by using

ls | grep -i "s.*m.*b.*"

I got the correct output (only a single file)

sambar .dia

 

Please tell me the explanation of this observance.

 

One more query please

In my mandrake 9.1 installation browsers(mozilla and Konqueror) are not able to access ftp sites. What may be the problem? Are settings to be changed to enable accessing FTP sites.

 

Thanks

Edited February 19, 2007 by Vaibhav

[neddie]

Grep uses regular expressions which are a very powerful way of specifying your search. Check out Wikipedia for more info.

 

Basically, a dot . represents "any character" and an asterisk * represents "the previously mentioned character 0 or more times". So the regular expression

s.*m

matches an s, followed by any number of any character, followed by an m. If for example you had

sa*m

then it would match sm, sam, saaaaaaaaaaam and so on.