Append to the end of a specific line

Question

Hopefully this is a simple question for someone out there. I'm pretty sure I know what I need to use, but I can't figure out how to make it work. Here's the issue:

I have a flat file database. Lets just call it file.db

Here are some sample lines from file.db

#file.db
#
line1|example|sample|name|flag|blah
line2|example|sample|name|flag|blah
line3|example|sample|name|flag|blah

Basically the script calculates a MD5 hash of a tar file. Lets say the hash of the tar file = 1234abcd

I need to append the MD5 sum and another separator (|) to a specific line in file.db

For example:

#file.db
#
line1|example|sample|name|flag|blah
line2|example|sample|name|flag|blah|1234abcd
line3|example|sample|name|flag|blah

The line that it gets appended to will of course be controlled by a variable. I have tried using sed and awk but just cannot figure out the syntax.

UPDATE

Thank you guys, have the solution now. Here is what I ended up doing:

HASH=`md5sum tmp/$URL.tgz | awk '{ print $1 }'`
DBLINE=5
awk -v OFS="|" -v l="$DBLINE" -v h="$HASH" 'NR==l{print $0,h;next}1' databases/$WEB > /tmp/$WEB.tmp && mv /tmp/$WEB.tmp databases/$WEB

Thank you Kent, and everyone else that answered.

What is in the variable? How is the line to be changed different to the others? — choroba, Apr 15 '13 at 09:33

score 1 · Answer 1 · answered Apr 15 '13 at 09:35

1

line=2
awk -v line="$line" 'FNR==line {printf("%s%s\n" $0, "|123abcd") ;next}
                     {print $0}' infile > newfile

answered Apr 15 '13 at 09:35

jim mcnamara

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Thank you, but I ended up finding a similar solution. See update in original post. – Atomiklan Apr 15 '13 at 10:49

Kent · Accepted Answer · 2013-04-15T10:31:38.973

0

try this awk one-liner:

line=2
awk -v OFS="|" -v l="$line" 'NR==l{print $0,"123abc";next}1'

with your example input:

kent$  echo "line1|example|sample|name|flag|blah
line2|example|sample|name|flag|blah
line3|example|sample|name|flag|blah"|awk -v OFS="|" -v l="$line" 'NR==l{print $0,"123abc";next}1'                                                                           
line1|example|sample|name|flag|blah
line2|example|sample|name|flag|blah|123abc
line3|example|sample|name|flag|blah

if you want to save the output back to your original:

awk '....' file.db > /tmp/file.db.tmp && mv file.db.tmp /path/to/your/file.db

EDIT

if you need a variable for md5 hash as well:

 line=2
 hsh="whatever"
 awk -v OFS="|" -v l="$line" -v h="$hsh" 'NR==l{print $0,h;next}1'

edited Apr 15 '13 at 10:31

answered Apr 15 '13 at 09:45

Kent

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Excellent, this appears to be working, but I can't seem to use a variable where you have hash currently (123abc) – Atomiklan Apr 15 '13 at 10:20
@user2272450 yes you can. see EDIT in answer. – Kent Apr 15 '13 at 10:31

score 0 · Answer 3 · edited May 23 '17 at 11:57

0

Take a look at this quiestion. I think, it has the answer for you. I can just add that you can use regex patterns in sed:

sed '/.*line2.*/ a |123asdfasdf' out.db

edited May 23 '17 at 11:57

Community

1
1

answered Apr 15 '13 at 09:46

user2256686

245
1
7

Thank you, but I ended up finding a similar solution. See update in original post. – Atomiklan Apr 15 '13 at 10:50

score 0 · Answer 4 · answered Apr 15 '13 at 10:12

0

set LN = 5
set MS = 1234abcd
sed -i.bak $LN's/$/|'$MS'/' file.db

this should work +

answered Apr 15 '13 at 10:12

Sidharth C. Nadhan

2,191
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Thank you, but I ended up finding a similar solution. See update in original post. – Atomiklan Apr 15 '13 at 10:50

Append to the end of a specific line

UPDATE

4 Answers4