From 78ca825a27ea02ed17be226f253cecb0e3a71daa Mon Sep 17 00:00:00 2001
From: Tom Ryder <tom@sanctum.geek.nz>
Date: Sat, 20 Aug 2016 17:27:04 +1200
Subject: Port path() to POSIX sh

That was a lot easier than I thought
---
 sh/shrc.d/path.sh | 93 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 sh/shrc.d/path.sh

(limited to 'sh/shrc.d/path.sh')

diff --git a/sh/shrc.d/path.sh b/sh/shrc.d/path.sh
new file mode 100644
index 00000000..22374310
--- /dev/null
+++ b/sh/shrc.d/path.sh
@@ -0,0 +1,93 @@
+# Function to manage contents of PATH variable within the current shell
+path() {
+
+    # The second argument, the directory, can never have a colon
+    case $2 in
+        *:*)
+            printf >&2 'path(): Illegal colon in given directory\n'
+            return 2
+            ;;
+    esac
+
+    # Check first argument to figure out operation 
+    case $1 in
+
+        # List current directories in $PATH
+        list|'') (
+            path=$PATH:
+            while [ -n "$path" ] ; do
+                dir=${path%%:*}
+                path=${path#*:}
+                [ -n "$dir" ] || continue
+                printf '%s\n' "$dir"
+            done
+            ) ;;
+
+        # Add a directory at the start of $PATH
+        insert)
+            if path check "$2" ; then
+                printf >&2 'path(): %s already in $PATH\n'
+                return 1
+            fi
+            PATH=${2}${PATH:+:"$PATH"}
+            ;;
+
+        # Add a directory to the end of $PATH
+        append)
+            if path check "$2" ; then
+                printf >&2 'path(): %s already in $PATH\n'
+                return 1
+            fi
+            PATH=${PATH:+"$PATH":}${2}
+            ;;
+
+        # Remove a directory from $PATH
+        remove)
+            if ! path check "$2" ; then
+                printf >&2 'path(): %s not in $PATH\n'
+                return 1
+            fi
+            PATH=$(
+                path=:$path:
+                path=${path%%:"$2":*}:${path#*:"$2":}
+                path=${path#:}
+                path=${path%:}
+                printf '%s\n' "$path"
+            )
+            ;;
+
+        # Check whether a directory is in $PATH
+        check) (
+            path=:$PATH:
+            [ "$path" != "${path%:"$2":*}" ]
+            ) ;;
+
+        # Print help output (also done if command not found)
+        help)
+            cat <<'EOF'
+path(): Manage contents of PATH variable
+
+USAGE:
+  path [list]
+    Print the current directories in PATH, one per line (default command)
+  path insert DIR
+    Add a directory to the front of PATH
+  path append DIR
+    Add a directory to the end of PATH
+  path remove DIR
+    Remove directory from PATH
+  path check DIR
+    Return whether DIR is a component of PATH
+  path help
+    Print this help message (also done if command not found)
+EOF
+            ;;
+
+        # Command not found
+        *)
+            printf >&2 'path(): Unknown command\n'
+            path help
+            return 2
+            ;;
+    esac
+}
-- 
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