grep query to list 1 line [which is fixed] and the next line after it [variable text]

Glenn D. · 01-20-2011, 06:07 AM

Hello,
How can I list the following with grep.
I want to extract 2 lines fron a text file

The fixed known part if it exists will static text and the text line after it will change.

A sample file
.
.
textline1
.
.
build: extracting built packages...
somename-2.6.36.3-16.1.i586.rpm
anothername2.6.36.3-16.1.i586.rpm
.
<eof>

In the above case it would return
build: extracting built packages...
somename-2.6.36.3-16.1.i586.rpm

If the fixed part does Not exist how can I return error code 1
Thanks Glenn

syg00 · 01-20-2011, 06:19 AM

what did your reading of the manpage indicate ?

AlucardZero · 01-20-2011, 06:20 AM

grep -A1 "build: extracting built packages" foofile

Code:

       -A NUM, --after-context=NUM
              Print NUM lines of trailing context after matching lines.  Places a line containing
              a group separator (--) between contiguous  groups  of  matches.   With  the  -o  or
              --only-matching option, this has no effect and a warning is given.

druuna · 01-20-2011, 06:21 AM

Hi,

grep -A1 "build: extracting built packages..." infile

Grep already tells you if the grep succeeded or not (echo $?)
0 - lines are found
1 - lines are not found
2 - an error occurred

Hope this helps.