/usr/bin/env shebang, check test -ef works, refactor

1 files changed, 18 insertions, 15 deletions

diff --git a/nextbin b/nextbin
index 3a7a4e6..006b158 100755
--- a/nextbin
+++ b/nextbin
@@ -1,14 +1,7 @@
-#!/bin/sh
+#!/usr/bin/env sh
 
 set -e
 
-die() {
-    fmt=$1
-    shift
-    printf "nextbin %s failed: $fmt\n" "$orig_exe" "$@" >&2
-    exit 1
-}
-
 usage() {
     # shellcheck disable=SC2016
     echo 'usage: nextbin [-v] "$0" "$@"' >&2
@@ -19,12 +12,21 @@ case "$1" in
     -*|'') usage; exit 1;;
     *) action="exec"
 esac
+
 orig_exe=$1
 shift
-exe_name=${orig_exe##*/}
 
+die() {
+    fmt=$1
+    shift
+    printf "nextbin %s failed: $fmt\n" "$orig_exe" "$@" >&2
+    exit 1
+}
+
+[ / -ef / ] || exec bash "$0" "$orig_exe" "$@" || die "test -ef doesn't work, and bash not found"
 [ -n "$PATH" ] || die 'PATH is empty'
 
+exe_name=${orig_exe##*/}
 path=$PATH
 phase=1
 found=
@@ -36,9 +38,7 @@ while :; do
                 phase=2
             fi
         elif [ "$exe" -ef "$orig_exe" ]; then
-            if [ -n "$found" ]; then
-                die 'duplicate PATH entries found'
-            fi
+            [ -z "$found" ] || die 'duplicate PATH entries found'
         elif [ -z "$found" ]; then
             found=$exe
         fi
@@ -49,6 +49,9 @@ while :; do
     esac
 done
 
-[ "$phase" != 1 ] || found=$(command -v "$exe_name") || die '%s is not in PATH' "$orig_exe"
-[ -n "$found" ] || die '%s is last instance' "$orig_exe"
-$action "$found" "$@"
+if [ "$phase" = 1 ]; then
+    found=$(command -v "$exe_name") || die '%s is not in PATH' "$exe_name"
+elif [ -z "$found" ]; then
+    die '%s is last instance' "$orig_exe"
+fi
+"$action" "$found" "$@"