Answer by cas for Convert file path from Linux to Windows format for Wine tool

1. Always double-quote your variables so that you don't need to care about spaces or shell meta-characters.

2. you can use sed or tr to convert /s to \. e.g. sed 's:/:\\:g' or tr '/' '\\' (note: because \ is the shell escape character, it needs to be escaped to be treated as a literal backslash).

3. Alternatively, bash's string manipulation operators will do the job (but aren't posix standard, so aren't portable). The only mistake you made there was in not quoting the variables.

But note that, as mentioned by @Michael Homer, it shouldn't be necessary to modify the path separator...I've certainly had no difficulty running wine program.exe /unix/path/to/file in the past.

resulting in:

#!/bin/bash

p1="$1"
p2="$2"

# optional transformation
p1="$(printf "%s" "$p1" | tr '/' '\\')"
p2="$(printf "%s" "$p2" | tr '/' '\\')"

wine /utils/wincmp.exe "$p1" "$p2"

or

#!/bin/bash

p1="${1//\//\\}"
p2="${2//\//\\}"

wine /utils/wincmp.exe "$p1" "$p2"

or even:

#!/bin/bash
wine /utils/wincmp.exe "${1//\//\\}" "${2//\//\\}"

(but this last version doesn't give you any opportunity to sanity-check the file arguments, or do any kind of option handling - e.g. with getopts)

Finally, you may want to reconsider your preference for a Windows diff tool, or at least conduct a more thorough survey before deciding (you've only evaluated a small subset of available tools and GUI wrappers). A Windows/wine based tool will not integrate pleasantly into Linux/UNIX-based development workflow.

(personally, I mostly use either diff -u or colordiff -u piped into less. Given that I'm working with text files, there's no need for a GUI interface. It's also identical to what I get from git diff etc. On the rare occasions I need a side-by-side diff, I mostly use sdiff).