NAME

redo-whichdo - show redo's search path for a .do file

SYNOPSIS

redo-whichdo <target>

DESCRIPTION

redo(1) and redo-ifchange(1) build their targets by executing a ".do file" script with appropriate arguments. .do files are searched starting from the directory containing the target, and if not found there, up the directory tree until a match is found.

To help debugging your scripts when redo is using an unexpected .do file, or to write advanced scripts that "proxy" from one .do file to another, you can use redo-whichdo to see the exact search path that redo uses, and the arguments it would use to run the .do file once found.

The output format contains lines in exactly the following order, which is intended to be easy to parse in sh(1) scripts:

Zero or more lines starting with "-", indicating .do files that were checked, but did not exist. If one of these files is created, the .do script for your target would change. You might want to call redo-ifcreate(1) for each of these files.
Exactly one line starting with "+", indicating the .do file that was the closest match.
Exactly one line starting with "1", indicating the first argument to the matching .do file.
Exactly one line starting with "2", indicating the second argument to the matching .do file.

EXAMPLE

Here's a typical search path for a source file (x/y/a.b.o). Because the filename contains two dots (.), at each level of the hierarchy, redo needs to search default.b.o.do, default.o.do, and default.do.

    $ redo-whichdo x/y/a.b.o

    - x/y/a.b.o.do
    - x/y/default.b.o.do
    - x/y/default.o.do
    - x/y/default.do
    - x/default.b.o.do
    - x/default.o.do
    - x/default.do
    - default.b.o.do
    + default.o.do
    1 x/y/a.b.o
    2 x/y/a.b

You might use redo-whichdo to delegate from one .do script to another, using code like this:

    out=$3
    redo-whichdo "$SRCDIR/$1" | {
        x1= x2= dofile=
        ifcreate=
        while read a b; do
            case $a in
              -)
                ifcreate="$ifcreate $b"
                ;;
              +)
                redo-ifcreate $ifcreate &&
                redo-ifchange "$b" || exit
                dopath="$b"
                dodir=$(dirname "$dopath")
                dofile=$(basename "$dopath")
                ;;
              1)
                x1="$b"
                ;;
              2)
                x2="$b"
                out="$PWD/$3"
                cd "$dodir" && . "./$dofile" "$x1" "$x2" "$out"
                exit
                ;;
            esac
        done
        exit 3
    }

REDO

Part of the redo(1) suite.

CREDITS

The original concept for redo was created by D. J. Bernstein and documented on his web site (http://cr.yp.to/redo.html). This independent implementation was created by Avery Pennarun and you can find its source code at http://github.com/apenwarr/redo.

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