Shell Programming and Scripting

I am trying to take the two line version of this:

mv myFile.txt myFile.txt.bak
sed 's/foo/bar/g' myFile.txt.bak > myFile.txt

and make it into a shell script with three parameters. First two parameters are the string and string replacement and the third is file. So far this is what I have but it still isnt working.

#!/bin/csh

mv $3 $3.bak
sed 's/$1/$2/g' $3.bak > $3

---------- Post updated at 06:06 PM ---------- Previous update was at 05:12 PM ----------

I changed it to

#!/bin/csh

set old_pattern=$1
set new_pattern=$2
set file_name=$3

mv $file_name $file_name.bak
sed -e "s/$old_pattern/$new_pattern/g" $file_name.bak > $file_name


I am assuming I am having trouble with strings with spaces but I still cant get it to work

I never use C Shell, but it looks generally OK to me.

If you think you're having trouble with spaces, try using quotes:

Code:

set old_pattern="$1"
set new_pattern="$2"

If your old_pattern or new_pattern use slashes (/) then you should change your sed expression to use something else

Code:

sed -e "s/$old_pattern/$new_pattern/g" $file_name.bak > $file_name
to
sed -e "s+$old_pattern+$new_pattern+g" $file_name.bak > $file_name

You should also test if the three arguments you expect are actually given.

But as you didn't post the error message, or say what's not working about it (i.e. what it does output), it's hard to say.

quotations worked, thank you

any idea how to apply this to any number of file?

One possibility:

If this is in a script called my_script, then

Code:

ls -1 *.txt | xargs -I{} ./my_script old_string new_string {}

thank you, but what if like the first script there is more than one file as a parameter, say three or four files to change strings in.

You can call my_script as many times as you need to.