I have a file, a.asc which is generated from a shell script:
-----BEGIN PGP MESSAGE-----
qANQR1DBwE4DR5PN6zVjZTcQA/9z5Eg94cwYdTnC7v+JUegQuJwHripqnyjFrEs/ejzKYCNmngbHHmf8V4K3uFkYyp74aFf+CdymA030RKs6ewOwkmqRW19oIXCgVe8Qmfg+/2KTq8XN
I want to remove the header, footer and the blank lines (---, Version etc;) and modify the same file. That is after I append my command in the script file, a.asc file should look like this (No blank lines):
qANQR1DBwE4DR5PN6zVjZTcQA/9z5Eg94cwYdTnC7v+JUegQuJwHripqnyjFrEs/ejzKYCNmngbHHmf8V4K3uFkYyp74aFf+CdymA030RKs6ewOwkmqRW19oIXCgVe8Q
I used awk command to identify the header, footer and blank lines.
How do I remove these lines from a.asc so that it is modified?
Thanx
Hi Hugo,
Couldnt make it work. I think I will have to use sed here.
Thanx
man awk --> NR
if ( NR = 4 ) {print $0}
sed also is an excelent choice.
Regards, hugo
Thanks Hugo but I guess I wanted to know if I could modify the same file using these commands. In other words, I would like to delete the header and blank line from a.asc itself.
system
April 18, 2002, 5:56pm
6
Your awk command finds the lines you do not want, so if you include the negative operator that hugo_perez mentioned, then you get all but those lines:
awk '$1 !~ /(^-----)|(^Version)|(^$)/' a.asc > a.ascNEW
But cannot modify a.asc directly. You will have to rename.
natty (if you have solarias) see and read the output of:
man 5 regexp
Thanx Hugo and Jimbo. I think I will have to use and a.ascNEW approach here.
grep is what you are looking for.
First use ^$ to remove any blank lines, then grep -v to remove unique lines in the file. Then redirect to a new filename.
cat filename |grep -v ^$ |grep -v "unique header" |grep -v "unique footer" > new.filename
Remember the -v option for grep will remove/ignore lines and send the rest to standard out.
system
April 19, 2002, 10:06am
10
I think the one awk process is a far superior solution than four processes piped together.
Is superior, in all the ways. If somebody doubts it, use the time command.
yea, yea, yea...:rolleyes: :o
I know that it wastes some amount of time and is firing off multiple processes...
I was going for simplicity. However, for single use items like removing blank lines grep -v ^$ is easy to remember.
I enjoy using awk as well, it is very cool. I am making my way through "The AWK Programming Language by Aho, Kerningan, Weinberger". Great book.
system
April 19, 2002, 11:59am
13
Thanks, Kelum_Magnus, for the awk book reference. To me, awk and vi were both very frustrating until I got the hang of them, now I love them.
And I definitely am not bashing grep. Every day you can see me using 4-5 piped greps.
But I strive for best practice. and I have improved my unix a huge amount, thanks to this forum and all the contributors, yourself included.
