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|
#!/bin/sh
# IMPORTANT NOTE: The "local" keyword is not defined in POSIX, so I've decided to work without it.
# For this reason, I do "$X/$f" instead of assigning local variables.
# Another thing to consider is that in recursive functions, backtracking logic
# CANNOT depend on variables, which are changed somewhere in the body before
# the recursive step.
cd "${0%/*}"
[ -z "$HOSTNAME" ] && HOSTNAME="$(hostname)"
if [ -z "$HOSTNAME" ]
then
echo "Set HOSTNAME variable to the system's name!" >/dev/stderr
exit 1
fi
if [ ! -f "./SYSTEM/$HOSTNAME" ]
then
echo "No configuration in ./SYSTEM for '$HOSTNAME'!" >/dev/stderr
exit 1
fi
# __merge_link <.FILES_DIR> <HOME_DIR>
__merge_link() {
while read -r f
do
# Output file doesn't exist -> Create link
# This is also true on broken symlinks
if [ ! -e "$2/$f" ]
then
if [ -h "$2/$f" ]
then
echo "Warn: '$2/$f' is a broken link to '$(readlink "$2/$f")', updating!"
rm "$2/$f"
fi
ln -s "$1/$f" "$2/$f"
# Output file is already linked to current -> Do nothing
elif [ -h "$2/$f" -a "$(readlink $2/$f)" = "$1/$f" ]
then
:
# Current file is a file (and output exists) -> Create link but also update current
elif [ -f "$1/$f" ]
then
if [ -f "$2/$f" ]
then
# When output is NOT a link inside .files,
# update current file with the contents of the output
# Otherwise,
# replace output file with (link to) current
if ! cmp -s "$1/$f" "$2/$f"
then
if [ -h "$2/$f" ]
then
real="$(readlink "$2/$f")"
if [ "${real#$PWD}" = "$real" ]
then
cp "$real" "$1/$f" 2>/dev/null
echo "Warn: '$2/$f' already existed, '$1/$f' updated with its contents!" >/dev/stderr
fi
else
cp "$2/$f" "$1/$f"
echo "Warn: '$2/$f' already existed, '$1/$f' updated with its contents!" >/dev/stderr
fi
fi
rm "$2/$f"
ln -s "$1/$f" "$2/$f"
else
echo "Error: '$2/$f' already exists and is not a regular file!"
fi
# Current file is a directory (and output exists) -> Link current's files & dirs in output directory
elif [ -d "$1/$f" ]
then
if [ -d "$2/$f" ]
then
# If output is a link to directory in .files, continuing with merge
# will place links inside a directory in .files, which is bad.
# Instead, we'll make the link to directory become a directory with
# links to all inner files.
if [ -h "$2/$f" ]
then
real="$(realpath "$2/$f")"
if [ "${real#$PWD}" != "$real" ]
then
rm "$2/$f"
mkdir "$2/$f"
while read -r ff
do
ln -s "$real/$ff" "$2/$f/$ff"
done <<FILES
$(ls -A1 "$real")
FILES
fi
fi
__merge_link "$1/$f" "$2/$f"
else
echo "Error: '$2/$f' already exists and is not a directory!"
fi
else
echo "Error: '$1/$f' is neither a file or directory!"
fi
done <<FILES
$(ls -A1 "$1")
FILES
}
link() {
while read -r dir
do
dir="${dir%%*/}"
if [ ! -d "./$dir" ]
then
echo "Unknown directory '$dir'!" >/dev/stderr
continue
fi
__merge_link "$PWD/$dir" "$HOME"
echo "Linked $dir"
done <"./SYSTEM/$HOSTNAME"
}
# __remove_link <.FILES_DIR> <HOME_DIR>
__remove_link() {
while read -r f
do
if [ -h "$2/$f" ]
then
real="$(realpath "$2/$f")"
# Output file exists and is a link to current -> Remove output
if [ "$real" = "$1/$f" ]
then
rm "$2/$f"
continue
# Output file exists and is a link in .files -> Do nothing (do not remove from .files)
# This is possible in the case when we have .files/X/A and .files/Y/A, and we linked
# .files/X but are now unlinking .files/Y
elif [ "${real#$PWD}" != "$real" ]
then
continue
fi
fi
if [ -d "$1/$f" -a -d "$2/$f" ]
then
__remove_link "$1/$f" "$2/$f"
fi
done <<FILES
$(ls -A1 "$1")
FILES
# See IMPORTANT NOTE, since we're aiming for full POSIX compatibility,
# the variable f will be overwritten by recursive calls, so this loop
# cannot be merged with the loop above (remove dirs on backtracking)
while read -r f
do
# Output file exists and is an empty directory -> Remove it
# We're assuming this directory was created by the script and/or the user
# will not care for empty dirs
if [ -d "$2/$f" -a -z "$(ls -A "$2/$f" 2>/dev/null)" ]
then
rm -r "$2/$f"
fi
done <<FILES
$(ls -A1 "$1")
FILES
}
unlink() {
while read -r dir
do
dir="${dir%%*/}"
if [ ! -d "./$dir" ]
then
echo "Unknown directory '$dir'!" >/dev/stderr
continue
fi
__remove_link "$PWD/$dir" "$HOME"
echo "Unlinked $dir"
done <"./SYSTEM/$HOSTNAME"
}
case "$1" in
(unlink) unlink ;;
(link|*) link ;;
esac
|
