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# Shortcut to switch to another directory with the same parent, i.e. a sibling
# of the current directory.
#
# $ pwd
# /home/you
# $ sd friend
# $ pwd
# /home/friend
# $ sd you
# $ pwd
# /home/you
#
# If no arguments are given and there's only one other sibling, switch to that;
# nice way to quickly toggle between two siblings.
#
# $ cd -- "$(mktemp -d)"
# $ pwd
# /tmp/tmp.ZSunna5Eup
# $ mkdir a b
# $ ls
# a b
# $ cd a
# pwd
# /tmp/tmp.ZSunna5Eup/a
# $ sd
# $ pwd
# /tmp/tmp.ZSunna5Eup/b
# $ sd
# $ pwd
# /tmp/tmp.ZSunna5Eup/a
#
# Seems to work for symbolic links.
sd() {
# Check argument count
if [ "$#" -gt 1 ] ; then
printf >&2 'sd(): Too many arguments\n'
return 2
fi
# Read sole optional argument
case $1 in
# Slashes aren't allowed
*/*)
printf >&2 'bd(): Illegal slash\n'
return 2
;;
# If blank, we try to find if there's just one sibling, and change to
# that if so
'')
# First a special case: root dir
case $PWD in
*[!/]*) ;;
*)
printf >&2 'sd(): No siblings\n'
return 1
;;
esac
# Get a full list of directories at this level; include dotfiles,
# but not the . and .. entries, using glob tricks to avoid Bash
# ruining things with `dotglob`
set -- ../[!.]*/
[ -e "$1" ] || shift
set -- ../.[!.]*/ "$@"
[ -e "$1" ] || shift
set -- ../..?*/ "$@"
[ -e "$1" ] || shift
# Check the number of matches
case $# in
# One match? Must be $PWD, so no siblings--throw in 0 just in
# case, but that Shouldn't Happen (TM)
0|1)
printf >&2 'sd(): No siblings\n'
return 1
;;
# Two matches; hopefully just one sibling, but which is it?
2)
# Push PWD onto the stack, strip trailing slashes
set -- "$1" "$2" "$PWD"
while : ; do
case $3 in
*/) set -- "$1" "$2" "${3%/}" ;;
*) break ;;
esac
done
# Pick whichever of our two parameters doesn't look like
# PWD as our sole parameter
case $1 in
../"${3##*/}"/) set -- "$2" ;;
*) set -- "$1" ;;
esac
;;
# Anything else? Multiple siblings--user will need to specify
*)
printf >&2 'sd(): Multiple siblings\n'
return 1
;;
esac
;;
# If not, simply set our target to that directory, and let `cd` do the
# complaining if it doesn't exist
*) set -- ../"$1" ;;
esac
# Try and change into the first parameter
# shellcheck disable=SC2164
cd -- "$1"
}
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