Re: grep -

[Bob Proulx]

leondd1995 wrote:
> ypcat hosts | grep st[1-4]-nttd 
> ...
> Now...  if I run the command in any particular directory /, /root,
> /tmp/ etc... the commard properly provided a list of all host that
> met that st[1-4]-nttd - which is the four listed above.
> 
> However, I unknowingly had an empty file named 'st1-nttd' (a file
> with the same name as one of the hosts I was greping for) while in
> /root.  I ran ypcat hosts | grep st[1-4]-nttd, from /root and the
> output only showed 'st1-nttd'.
> ...
> Is this a bug in grep or am I simply using bad syntax?

You are not quoting your grep expression.  Because [1-4] is a shell
file glob wildcard it will match any files that match it.  You need to
keep it from matching filenames so that the string will be passed to
the command verbatim.

  ypcat hosts | grep "st[1-4]-nttd"

In the bash man page:

   Pathname Expansion
       After  word  splitting,  unless  the -f option has been set, bash scans
       each word for the characters *, ?, and [.  If one of  these  characters
       appears,  then  the word is regarded as a pattern, and replaced with an
       alphabetically sorted list of file names matching the pattern.   If  no
       matching  file  names  are found, and the shell option nullglob is dis-
       abled, the word is left unchanged.  ...

Bob