I'm trying to make a shell script that can change class names in source files.

The following will run without an error message but it doesn't do exactly what I want.

sed 's/from/to/g' somefile_containing_from.txt

That command will replace all occurrences of the word "from" to "to" while printing out the contents of the file. What I need is something where it only matches when there is a non-letter before and after the "from".

Due to the problem in the above command, the following undesired replacements happen:

File contents for student.java before running through sed command:

public class student
{
   private student[] topstudent;
}

using command:

sed 's/student/Student/g' student.java

Prints the following:

public class Student
{
   private Student[] topStudent;
}

Notice that the variable name changed because it found "student" in the output even though topstudent was not the class name.