How can I view all historical changes to a file in SVN

If you want to see whole history of a file with code changes :

svn log --diff [path_to_file] > log.txt

There's no built-in command for it, so I usually just do something like this:

#!/bin/bash

# history_of_file
#
# Outputs the full history of a given file as a sequence of
# logentry/diff pairs.  The first revision of the file is emitted as
# full text since there's not previous version to compare it to.

function history_of_file() {
    url=$1 # current url of file
    svn log -q $url | grep -E -e "^r[[:digit:]]+" -o | cut -c2- | sort -n | {

#       first revision as full text
        echo
        read r
        svn log -r$r $url@HEAD
        svn cat -r$r $url@HEAD
        echo

#       remaining revisions as differences to previous revision
        while read r
        do
            echo
            svn log -r$r $url@HEAD
            svn diff -c$r $url@HEAD
            echo
        done
    }
}

Then, you can call it with:

history_of_file $1

You could use git-svn to import the repository into a Git repository, then use git log -p filename. This shows each log entry for the file followed by the corresponding diff.

Slightly different from what you described, but I think this might be what you actually need:

svn blame filename

It will print the file with each line prefixed by the time and author of the commit that last changed it.