Login or Register to Ask a Question and Join Our Community


UNIX for Dummies Questions & Answers

Change Specific Line of a File

 
Thread Tools Search this Thread
Top Forums UNIX for Dummies Questions & Answers Change Specific Line of a File
# 1  
Old 08-18-2008
Change Specific Line of a File
Hi everyone,

I am attempting to do something that should be very simple. How do I replace a specific line of a file with different text, and then save that file to its original name? I believe I want to use the sed command with the c option, but I after trying many times, I can't get the right syntax. I am using bash.

Mike
# 2  
Old 08-18-2008
Code:
different_text="this is the new text"
awk -v diff="$different_text" '{ if(NR==4) { print diff}
                              else {print $0} } ' filename > newfilename

# 3  
Old 08-18-2008
Code:
sed '42c\'"I am the walrus" file >newfile

# 4  
Old 08-18-2008
Hi,

Yes I was trying to something similar. However, that still does not work. Is that the syntax for bash?
# 5  
Old 08-18-2008
Works here, Ubuntu 7.something, bash 3.2.13. The sed version is what decides whether it works or not, though. I have GNU sed version 4.1.5

Code:
vnix$ sed '4c\'"I am the walrus" /etc/motd
Linux left 2.6.20-17-386 #2 Thu Jul 10 00:02:05 UTC 2008 i686

The programs included with the Ubuntu system are free software;
I am the walrus
individual files in /usr/share/doc/*/copyright.

Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
applicable law.

Try putting the change on a different line:

Code:
sed '42c\
I am the walrus' file >newfile

Yes, you would put a backslash and a newline between "42c" and "I am the walrus". Yes, that's right. No, I'm not kidding. (Nothing personal, it's just that the normal reaction to this instruction is "I tried it and it doesn't work." "So did you put a backslash and a newline between the two lines?" "No, was I supposed to?")
Last edited by era; 08-18-2008 at 07:10 PM..
# 6  
Old 08-18-2008
Perhaps i am not going about this correctly. Here is my "test file":

$cat test.txt
coo
coo
ca
choo
$

Let's say I simply want to replace the first line (coo) with koo.

With the above suggestion:

$sed '1c\'"koo" test.txt
sed: 1: "1c\koo": extra characters after \ at the end of c command

Putting a space before "koo" yields:

$sed '1c\' "koo" test.txt
sed: koo: No such file or directory
coo
ca
choo

I get closer by typing:

$sed '1c\
> koo' test.txt
koocoo
ca
choo

But it's still not right. I am using the bash that comes with OS X Leopard. Any ideas on what's going wrong?
# 7  
Old 08-18-2008
Probably your version of sed is different; OSX is traditionally BSD based.

Try this:

Code:
sed '1c\
koo\
' test.txt

 
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

awk to change specific string to new value if found in text file

I am trying to use awk to change a specific string in a field, if it is found, to another value. In the tab-delimited file the text in bold in $3 contains the string 23, which is always right before a ., if it is present. I am trying to change that string to X, keeping the formatting and the... (3 Replies)
Discussion started by: cmccabe
3 Replies

2. Shell Programming and Scripting

Extract specific line in an html file starting and ending with specific pattern to a text file

Hi This is my first post and I'm just a beginner. So please be nice to me. I have a couple of html files where a pattern beginning with "http://www.site.com" and ending with "/resource.dat" is present on every 241st line. How do I extract this to a new text file? I have tried sed -n 241,241p... (13 Replies)
Discussion started by: dejavo
13 Replies

3. Shell Programming and Scripting

To change Specific Lines in An XML file

hi Guys, this is my requirement, there is a huge xml file of this i have to change 3 lines with out opening the file /users/oracle > cat lnxdb-pts-454.xml|egrep "s_virtual|s_cluster|s_dlsnstatus" <cluster_port oa_var="s_clusterServicePort">9998</cluster_port> <host... (2 Replies)
Discussion started by: smarlaku
2 Replies

4. Shell Programming and Scripting

how to change specific value for a entry in the file

Hello All, can someone please suggest me a one line command to change a specific value that is associated to an entry in the file. for example #more schedulefile quartz.job.manual.bonus.schedule=0 0 9 ? * * # it should be changed to #more schedulefile... (5 Replies)
Discussion started by: bobby320
5 Replies

5. UNIX for Dummies Questions & Answers

How can I search and change an specific string in a file

Dear All, New to Linux/Unix OS, my Linux version is 2010 x86_64 x86_64 x86_64 GNU/Linux As titled, I wonder if you can help to provide a solution to find and change an specific string in a file The file include a lots of data in following configuration but might be various in... (3 Replies)
Discussion started by: axel
3 Replies

6. Shell Programming and Scripting

How to change a number on a specific line with cshell or shell?

Hello all, I need to change a number in a file by adding some residuals respectively To make it clear, I need to add 0.11 to the number between 24-28 (which is below the SECON) for all the lines starting with FRR1 or I need to add 0.13 to the number between 24-28 (which is below the... (9 Replies)
Discussion started by: miriammiriam
9 Replies

7. Shell Programming and Scripting

How to change a number on a specific lines in a file with shell?

Hello My problem is that I want to change some specific numbers in a file. It is like, 2009 10 3 2349 21.3 L 40.719 27.388 10.8 FRO 7 0.8 1.1LFRO 2.6CFRO 1.1LMAM1 GAP=157 1.69 5.7 5.9 5.8 0.5405E+01 0.4455E+00 0.1653E+02E STAT SP IPHASW D HRMM SECON CODA AMPLIT... (11 Replies)
Discussion started by: miriammiriam
11 Replies

8. Shell Programming and Scripting

Change specific ip address in a file

I need to change a line from a xen cfg file using sed if it's possible. The original line is: vif = I want to change ONLY the IP address of the second part ==> ip=10.1.10.4 to another IP --> ip=192.222.11.6 The first one ip=123.456.789.123 keeps untouchable. My new line shoud... (9 Replies)
Discussion started by: iga3725
9 Replies

9. UNIX for Dummies Questions & Answers

Script to change/find/delete/install a specific file

Hi Very much a newbie to UNIX & scripting, but have identified an area within work that would benefit from being automated, as its repeated manually very often, and it looks like the ideal first script! What I need to do is change directory to a users home (cd ~), and then find and remove a... (6 Replies)
Discussion started by: Great Uncle Kip
6 Replies

10. Shell Programming and Scripting

How to change a specific character in a file

Hi, I have a data file with following structure: a|b|c|d|3|f1|f2|f3 a|b|c|d|5|f1|f2|f3|f4|f5 I want to change this data to: a|b|c|d|3|f1;f2;f3 a|b|c|d|5|f1;f2;f3;f4;f5 Data in column 5 tells the number of following fields. All fields delimiter after the 5th column needs to be... (6 Replies)
Discussion started by: sdubey
6 Replies
Login or Register to Ask a Question