sed awk append after a line

I have a text file "file.txt"
#cat "file.txt"
line 1
line 2
line 3
line 5
line 6
#

I wanted to use sed/awk to append "line 4" after "line 3"

so the file should look like this
line 1
line 2
line 3
line 4
line 5
line 6
LVL 7
martin_2110Asked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

ozoCommented:
sed '3a\
line 4
'
0
Kerem ERSOYPresidentCommented:
Hi,

cat file.txt | sed -e 's/line 3/line 3\nline 4/'

Will do.

Cheers,
K.
0
Kerem ERSOYPresidentCommented:
of course you need to redirect the output to a temporary file and remove with the original such as this:

cat file.txt | sed -e 's/line 3/line 3\nline 4/' > /tmp/filenew ; mv /tmp/filenew file.txt

Cheers,
K.
0
Big Business Goals? Which KPIs Will Help You

The most successful MSPs rely on metrics – known as key performance indicators (KPIs) – for making informed decisions that help their businesses thrive, rather than just survive. This eBook provides an overview of the most important KPIs used by top MSPs.

ozoCommented:
# cat file.txt
line 1
line 2
line 3
line 5
line 6
# sed -i.bak '3a\
line 4
' file.txt
# cat file.txt
line 1
line 2
line 3
line 4
line 5
line 6
0
martin_2110Author Commented:
Any one got something a little less quick and dirty. Perhaps something with awk? My lines are not as simple as my example Think of lines with lots of special chars.
0
Kerem ERSOYPresidentCommented:
Yeah but in any case you'll escape any special character with \

be it sed or awk you need to escape them porperly for your regexp processor won't misinterpret them ..
0
ozoCommented:
Do you need to append special characters?
Are special characters needed to identify the line to append after?
0
Kerem ERSOYPresidentCommented:
yeah can you post an example ??

As far as I understand it is not in a fixed position. So what you need is just find and replace. But you say the regexp for match are rather complex.


0
martin_2110Author Commented:
Something like this. I want to insert the bold lines.

# To enable a cache of proxied content, uncomment the following lines.
# See http://httpd.apache.org/docs/2.2/mod/mod_cache.html for more details.
#
#<IfModule mod_disk_cache.c>
#   CacheEnable disk /
#   CacheRoot "/var/cache/mod_proxy"
#</IfModule>
#
#</IfModule># End of proxy directives.
### Section 3: Virtual Hosts
#
# VirtualHost: If you want to maintain multiple domains/hostnames on your
# machine you can setup VirtualHost containers for them. Most configurations
# use only name-based virtual hosts so the server doesn't need to worry about
# IP addresses. This is indicated by the asterisks in the directives below.
#
# Please see the documentation at
# <URL:http://httpd.apache.org/docs/2.2/vhosts/>
# for further details before you try to setup virtual hosts.
#
# You may use the command line option '-S' to verify your virtual host
# configuration.


0
Kerem ERSOYPresidentCommented:
sed -i "s/### Section 3: Virtual Hosts/#\</IfModule\>\n# End of proxy directives.\n### Section 3: Virtual Hosts/"  httpd.conf
0
ozoCommented:
sed '/#<\/IfModule>$/a\
# End of proxy directives.
'  file.txt
0
Kerem ERSOYPresidentCommented:
oops sorry I've forgotten to escape some chars. The true working version is here:

sed -i "s/### Section 3\: Virtual Hosts/#\<\/IfModule\>\n# End of proxy directives.\n\n### Section 3: Virtual Hosts/"  httpd.conf
0
Kerem ERSOYPresidentCommented:
or better:
sed -i "s/### Section 3\: Virtual Hosts/#\<\/IfModule\>\n# End of proxy directives.\n\n&/"  httpd.conf

& will expand to the matching string
0
ghostdog74Commented:

awk '/^#<\/IfModule>/{
    getline
    print
    print "#</IfModule>"
    print "#End of proxy directives."
    next
}1' file

Open in new window

0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
martin_2110Author Commented:
Thanks both. The awk solution was what i was looking for.
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Shell Scripting

From novice to tech pro — start learning today.