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Old 04-19-2012, 11:52 AM   #1
rabir
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Registered: Nov 2011
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Question How To Edit a File Through Bash Script


Dear All

I wanna try to write a bash script that automatically configure my linux server. But i need to know the commands that "disable all lines of that file or specific file that i mension it." as well as want to input my desired lies through bash commands.

As cat>> myfile can append my file but it does not work in bash.

Help anyone.
 
Old 04-19-2012, 12:08 PM   #2
kbp
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For that specific requirement I'd probably use:
Code:
perl -ni -e 'print unless /<regex>/' /path/to/file
For editing a specific line in a file:
Code:
perl -pi -e 's/<regex>/<replacement>/g' /path/to/file
To create a file:
Code:
cat <<EOF > /path/to/file
content
$myvar
content
EOF
To create a file without shell interpretation (handy when generating a script):
Code:
cat <<'EOF' > /path/to/file
content
PATH=$HOME/bin:$PATH
content
EOF
 
Old 04-19-2012, 12:09 PM   #3
dayid
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Location: Austin, TX
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Quote:
Originally Posted by rabir View Post
Dear All

I wanna try to write a bash script that automatically configure my linux server. But i need to know the commands that "disable all lines of that file or specific file that i mension it." as well as want to input my desired lies through bash commands.
To "disable all lines" you would simple comment out the lines (or blank them)

To blank the file, simple:
Code:
: > file
To comment out all lines:
Code:
sed -e 's/^/#/g' file > tmp && mv tmp file
To add your own text to something you most likely want "echo" along with "read":
Code:
echo -n "What is your hostname? "
read ANSWER
echo "Hostname: $ANSWER" >> file
That's the very basics. For anything more complicated you'll need to give more context to work with.
 
Old 04-24-2012, 04:09 AM   #4
rabir
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Registered: Nov 2011
Posts: 18

Original Poster
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Thank you very much "dayid" for your help.

problem # 1
the problem is that -->in a file first i want to search specific line & make it disable
as grep -n "error" /etc/named.conf
then
change according to the result.

Problem # 2
How do i get my Lan card hardware address ?

Problem # 3
suppoese i take a value from user as "read variable1" & have to reverse it & as well as truncate according to my choice & again use it as a string


thanks again for help
 
Old 04-24-2012, 04:37 AM   #5
grail
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Show us what you have tried regarding each of the questions and we can help guide you the answer.

For your first question, have a look at each of the sed answers provided already.
 
  


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