UNIX for Dummies Questions & Answers

Hi,

I need to use a double grep so to speak. I need to grep for a particular item say BOB and then for each successful result I need to grep for another item say SMITH.

I tried grep "BOB" filename | grep "SMITH"

but it does not seem to work.

I can achieve my desired result using an intermediate temporary file but I am trying to avoid that. Is there someway to set up a piping assembly line? I looked at the MAN pages but did not find that struck me as useful but I am new to UNIX so I thought I would ask here...

Code:

$ echo 'BOB SMITH' | grep BOB | grep SMITH
BOB SMITH
$

There's no reason it shouldn't work. Could you post some data from the input file, and the version of yours that didn't work?

Okay that works no problem

But supposing Bob Smith was in a file. I need to grep for Bob in a file and then grep again to make sure it contains Smith. The two are not side by side so I have to do two greps....

Should I be using fgrep? If so how?

Code:

$ echo 'BOB SMITH' > file
$ grep BOB < file | grep SMITH
BOB SMITH
$

I repeat:

There's no reason your first version shouldn't work. Could you post some data from the input file, and the version of yours that didn't work?

GNU grep 2.5.3

Copyright (C) 1988, 1992-2002, 2004, 2005 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
---------
What you posted above works but I have some questions/concerns:

1) What is the "<" character for? When I tried out your code I left it out and the code executed fine so I am wondering if it is really necessary.
2) When I create a file and put BOB on one line and SMITH on the other your code fails. Why? It is this type of situation I have problems with.

grep checks by line, not by file.

Is your example of Bob on one line and Smith on another what you are trying to accomplish? Merely to see if two things exist inside a file anywhere?

Code:

> cat file158
BOB
TED
HENRY
SMITH

> RESULT=`tr -d "\n" <file158 | grep "BOB" | grep "SMITH" | tr "[:print:]" "Y" | tr -s "Y"`
> echo $RESULT
Y

> RESULT=`tr -d "\n" <file158 | grep "BOB" | grep "SMITY" | tr "[:print:]" "Y" | tr -s "Y"`
> echo $RESULT