find and replace character

[sachrath]

I am having a huge file .
I need to find a chaacter only in the last line and replace it with another characted
I am not a UNIX expert , so would like do it with SED one liner .
Any help is appreciated

Thx
Sachin Rath

 

[PHV]

something like this ?
sed '$s!x!y!' /path/to/input >output

Hope This Helps, PH.
Want to get great answers to your Tek-Tips questions? Have a look at FAQ219-2884 or FAQ222-2244

 

[CaKiwi]

To change A to B in the last line of a file, try

sed '$s/A/B/' infile > oufile

CaKiwi

 

[sachrath]

My file name is x.parm

and the last line number of my file is 37 & I need to replace 90 with 91 so I tried

sed '37s/90/91/' x.parm > x.parm .

Where am I commiting a mistake ???

Sachin

 

[PHV]

x.parm > x.parm
The shell redirection will erase your file before sed read it.
You may try this:
sed '$s/90/91/' x.parm > x.$$ && mv x.$$ x.parm

Hope This Helps, PH.
Want to get great answers to your Tek-Tips questions? Have a look at FAQ219-2884 or FAQ222-2244

 

[CaKiwi]

You can't create the output file with the same name as the input file. Try

sed '$s/90/91/' x.parm > tmp.parm && mv tmp.parm x.parm

CaKiwi

 

[CaKiwi]

You're always 1 step ahead of me PHV!

CaKiwi

 

[sachrath]

Thx guys ...it worked .

Is this advisable to find & replace in the same way for very huge files as well.

Thx
Sachin Rath

 

[PHV]

You may have to consider df to ensure enough place is free in the file system.

Hope This Helps, PH.
Want to get great answers to your Tek-Tips questions? Have a look at FAQ219-2884 or FAQ222-2244

 

[sachrath]

Yeah , I had checked the space which looks enough .

Now I know how to go to a line in a file to follow up with further operations .

Thx again
Chao
Sachin

 

[Ygor]

If you have perl then you can edit files in place...

eg.1:[tt] perl -pi -e '$.==37 && s/90/91/' x.parm[/tt]
eg.2:[tt] perl -pi -e 'eof && s/90/91/' x.parm[/tt]