Add mex(1df)

1 files changed, 53 insertions, 0 deletions

diff --git a/bin/mex b/bin/mex
new file mode 100755
index 00000000..005149d8
--- /dev/null
+++ b/bin/mex
@@ -0,0 +1,53 @@
+#!/bin/sh
+# Make the first non-executable instance of files with the given names in $PATH
+# executable
+self=mex
+
+# Check we have at least one argument
+if [ "$#" -eq 0 ] ; then
+    printf >&2 '%s: At least one name required\n' "$self"
+    exit 2
+fi
+
+# Iterate through the given names
+for name ; do
+
+    # Clear the found variable
+    found=
+
+    # Start iterating through $PATH, with colon prefix/suffix to correctly
+    # handle the fenceposts
+    path=:$PATH:
+    while [ -n "$path" ] ; do
+
+        # Pop the first directory off $path into $dir
+        dir=${path%%:*}
+        path=${path#*:}
+
+        # Check $dir is non-null
+        [ -n "$dir" ] || continue
+
+        # If a file with the needed name exists in the directory and isn't
+        # executable, we've found our candidate and can stop iterating
+        if [ -f "$dir"/"$name" ] && ! [ -x "$dir"/"$name" ] ; then
+            found=$dir/$name
+            break
+        fi
+    done
+
+    # If the "found" variable was defined to something, we'll try to change its
+    # permissions
+    if [ -n "$found" ] ; then
+        chmod +x -- "$found" || ex=1
+
+    # If not, we'll report that we couldn't find it, and flag an error for the
+    # exit status
+    else
+        printf >&2 '%s: No non-executable name "%s" in PATH\n' "$self" "$name"
+        ex=1
+    fi
+done
+
+# We exit 1 if any of the names weren't found or if changing their permissions
+# failed
+exit "${ex:-0}"