OT: Linux Shell Script

Hey guys,

Ignore this if you are not familiar with Linux. I am throwing this out
because I expected it to work and can't get it working.

I am trying to create a bash script to delete two lines in a file only if
they are directly connected to one another.

For example if I had a file "file.txt" with the following lines

1

2

3

4

5

And I wanted to delete the lines with 3 & 4 but only if they were together.
i.e. I want to make sure I am not deleting if they are:

1

3

2

4

5

I know I could do

sed '/3/d' -i file.txt;sed '/4/d' -i file.txt

but that doesn't make sure they are directly together

I tried

sed '/3$\r\n4/d' -i file.txt

But it seems either it doesn't match or I am using the incorrect regular
expression

I know I could also do

cat file.txt | grep -v 3 | grep -v 4 > file.txt

but still not making sure it is one line. Any thoughts would be
appreciated. I believe there should be a way to do this with sed but I
wouldn't call myself a guru on the great intricacies of sed. If not then I
will just use expect, but I wanted to keep it simplistic.

I know with expect I can do

expect -re "\n3\r\n4" { exec sed '/3/d' -i file.txt;sed '/4/d' -i file.txt }

And that verifies the two lines are together and then I can delete the files
based off of them being together but I was hoping to stick with a simple
bash shell script for this task.

Regards,

Tyson Scott - CCIE #13513 R&S, Security, and SP

Technical Instructor - IPexpert, Inc.

Mailto: tscott_at_ipexpert.com

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Received on Wed Apr 28 2010 - 00:19:49 ART