cd up-forward

up.sh

# INSTALL:
#   alias up='source /path/to/up.sh'
#
# USAGE:
#   $ up        = cd ..
#   $ up 2      = cd ../..
#   $ up 3      = cd ../../..
#   $ up foo    = cd to the nearest `foo' directory in the ancestor path.
#       ex) At /foo/bar/baz/      , then cd to /foo/
#       ex) At /foo/bar/foo/baz/  , then cd to /foo/bar/foo/
#       ex) At /bar/baz/          , then shows error
#   $ up a/b    = cd to the nearest `a/b' path in the ancestor path.
#       ex) At /a/b/c/d/          , then cd to /a/b/
#
#   Note: `up 2` at /1/2/3/4/5/ is `cd /1/2/`, not `cd ../..`.
#
# LICENSE:
#   Public domain. Use this at your own risk.

$(
    /usr/bin/env perl -e '
        my ($curdir, $target) = @ARGV;
        if ($target eq "") {
            print "cd ..";
        } elsif ((my $moveto = "$curdir/") =~ s|^(.*/$target/).+$|$1|) {
            print "cd ", $moveto;
        } elsif ($target =~ /^\d+$/) {
            print "cd ", ("../" x $target);
        } else {
            print STDERR "No such directory: $target\n";
        }
    ' `pwd` "$1"
)