Shell Programming and Scripting

I want to run some unix commands on one file..let say if i change the name and that name of file is present already. I dnt want to change that presnt file but instead of that make another one with different name

eg.. usa.txt if it is there make usa.txt.1 something like that

Also one more thing I was confuse with was is it possible when we append somehing in a file..is it possible that it will again change the persmissions of the files automatically without using chmod

1.
renaming harmlessly

Code:

#/bin/ksh
srcfile=/path/to/myfile.dat
cnt=1
while [[  -f ${srcfile}.${cnt} ]]
do
   cnt=$(( $cnt + 1 ))
done
mv ${srcfile} ${srcfile}.${cnt}
newname=${srcfile}.${cnt}

2.
If a file already exists and you write to you do not change permissions. You have to explicitly chmod to do that. You can only change permissions on a file if you own it or you are running as root.

Thanks 4 reply..

Friend one question, you use (( parenthesis )) isnt this is bash ?

$(( )) is for POSIX shell integer arithmetic - bash, ksh, zsh anfd freiends.

POSIX is a standard, part of which defines how a shell language is supposed to work.

did you try to run??? i tried its giving error..

One syntax error - note the minor change on line 3, the "while" line. my bad.

If you have more problems, 'its giving error' is not going to help you. Or us. You need to show EXACTLY what the error message is.