Replace 8th and 9th characters in file permanently

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1

Good evening,

I have a file and wish to replace the 8th and 9th characters on the first line only no matter what they are with 44 and the file permanantly changed.

e.g. file example.txt before change:

123456789123456
hi how are you
blah
blah

file example.txt after change:

123456744123456
hi how are you
blah
blah

All answers much appreciated.

2

Try:

perl -i -pe 's/(.{7})../${1}44/ if $.==1' example.txt
3

Works perfectly.

Many thanks.

---------- Post updated 11-03-11 at 04:11 AM ---------- Previous update was 11-02-11 at 06:36 PM ----------

Morning,

I have now been asked for it in a bash script.

No perl.

Any ideas

Thanks in advance.

4 
 
$ sed  '1 s/\(.......\)..\(.*\)/\144\2/' test 
123456744123456
hi how are you
blah
blah

---------- Post updated at 03:10 PM ---------- Previous update was at 03:09 PM ----------

 
$ sed '1 s/\(.\{7\}\)../\144/' test
123456744123456
hi how are you
blah
blah
5

If your file is big, the following will take no time:

echo 44 |dd of=test bs=1 seek=7 count=2 conv=notrunc