Merge independent repo conflink into this one

Merge remote-tracking branch 'conflink/master'

diff --git a/conflink b/conflink
new file mode 100755 (executable)
index 0000000..8431c16
--- /dev/null
+++ b/conflink
@@ -0,0 +1,83 @@
+#!/bin/bash
+
+source /a/bin/errhandle/errcatch-function
+source /a/bin/errhandle/bash-trace-function
+
+errcatch
+
+m() {
+    echo "$*"
+    "$@"
+}
+s() { sudo "$@"; }
+lnf() { /a/exe/lnf "$@"; }
+
+
+shopt -s nullglob
+shopt -s extglob # note, already set with bash -l
+
+# If we make a link back to the root, we stop going deeper into subdir_files.
+# This makes it so we can do subdir directories.
+#
+# Also note, under filesystem/, symlinks are expanded.
+
+subdir-link-r() {
+    local root="$1"
+    local targets=()
+    if [[ $2 ]]; then
+        targets=( "$2"/!(.git|..|.) )
+    else
+        for f in "$1"/!(.git|..|.); do
+            [[ -d $f ]] && targets+=("$f") ||:
+        done
+    fi
+    local below="$( readlink -f "$root/..")"
+    for path in "${targets[@]}"; do
+        local fullpath="$(readlink -f "$path")"
+        #e $fullpath $below # debug
+        if [[ -f $path || $(dirname $(readlink -f "$fullpath")) == "$below" ]]; then
+            m lnf -T "$path" "$HOME/${path#$root/}"
+        elif [[ -d "$path" ]]; then
+            subdir-link-r "$root" "$path"
+        fi
+    done
+}
+
+common-file-setup() {
+    local dir fs x
+    for dir in "$@"; do
+        fs=$dir/filesystem
+        if [[ -e $fs && $USER == ian ]]; then
+            # note, symlinks get resolved, not copied.
+            m s cp -RLT --preserve=mode,timestamps $fs /
+        fi
+        if [[ -e $dir/subdir_files ]]; then
+            subdir-link-r $dir/subdir_files
+        fi
+        local x=( $dir/!(subdir_files|filesystem|machine_specific|..|.) )
+        (( ${#x[@]} >= 1 )) || continue
+        m lnf ${x[@]} ~
+    done
+}
+
+all_dirs=({/a/c,/p/c}{,/machine_specific/$HOSTNAME})
+# note, we assume a group of hosts does not have the
+# same name as a single host, which is no problem on our scale.
+for x in /p/c/machine_specific/*.hosts; do
+    if grep -qxF $HOSTNAME $x; then all_dirs+=( ${x%.hosts} ); fi
+done
+
+c_dirs=(/a/c{,/machine_specific/$HOSTNAME})
+case $USER in
+    ian)
+        # p needs to go first so .ssh link is created, then config link inside it
+        common-file-setup ${all_dirs[@]}
+        sudo -u traci "$BASH_SOURCE"
+        ;;
+    traci)
+        common-file-setup ${c_dirs[@]}
+        ;;
+    *)
+        echo "$0: error: unexpected user"; exit 1
+        ;;
+esac