Add ad()

1 files changed, 77 insertions, 0 deletions

diff --git a/sh/shrc.d/ad.sh b/sh/shrc.d/ad.sh
new file mode 100644
index 00000000..d3e5a90a
--- /dev/null
+++ b/sh/shrc.d/ad.sh
@@ -0,0 +1,77 @@
+# Find an abbreviated path
+ad() {
+
+    # Check argument count
+    if [ "$#" -ne 1 ] ; then
+        printf >&2 'ad(): Need just one argument\n'
+        return 2
+    fi
+
+    # Change the positional parameters from the abbreviated request
+    # to any matched directory
+    set -- "$(
+
+        # Clean up and anchor the request
+        req=${1%/}/
+        case $req in
+            (/*) ;;
+            (*) req=${PWD%/}/${req#/}/ ;;
+        esac
+
+        # Start building the target directory; go through the request piece by
+        # piece until it is used up
+        dir=
+        while [ -n "$req" ] ; do
+
+            # Chop the next front bit off the request and add it to the dir
+            dir=${dir%/}/${req%%/*}
+            req=${req#*/}
+
+            # If that exists, all is well and we can keep iterating
+            [ -d "$dir" ] && continue
+
+            # Set the positional parameters to a glob expansion of the
+            # abbreviated directory given
+            set -- "$dir"*
+
+            # Iterate through the positional parameters filtering out
+            # directories; we need to run right through the whole list to check
+            # that we have at most one match
+            entd=
+            for ent ; do
+                [ -d "$ent" ] || continue
+
+                # If we already found a match and have found another one, bail
+                # out
+                if [ -n "$entd" ] ; then
+                    printf >&2 'ad(): More than one matching dir for %s*:\n' \
+                        "$dir"
+                    printf >&2 '%s\n' "$@"
+                    exit 1
+                fi
+
+                # Otherwise, this can be our first one
+                entd=$ent
+            done
+
+            # If we found no match, bail out
+            if [ -z "$entd" ] ; then
+                printf >&2 'ad(): No matching dirs: %s*\n' "$dir"
+                exit 1
+            fi
+
+            # All is well, tack on what we have found and keep going
+            dir=$entd
+
+        done
+
+        # Print the target
+        printf '%s\n' "$dir"
+    )"
+
+    # If the subshell printed nothing, return with failure
+    [ -n "$1" ] || return
+
+    # Try to change into the determined directory
+    command cd -- "$@"
+}