1 files changed, 40 insertions, 0 deletions
diff --git a/remove-shell b/remove-shell
new file mode 100755
index 0000000..1e6b739
--- /dev/null
+++ b/remove-shell
@@ -0,0 +1,40 @@
+#!/bin/sh -e
+
+if test $# -eq 0
+then
+	echo usage: $0 shellname '[shellname ...]' 1>&2
+	exit 1
+fi
+
+file=/etc/shells
+# I want this to be GUARANTEED to be on the same filesystem as $file
+tmpfile=${file}.tmp
+otmpfile=${file}.tmp2
+
+set -o noclobber
+
+trap "rm -f $tmpfile $otmpfile" EXIT
+        
+if ! cat $file > $tmpfile
+then
+        cat 1>&2 <<EOF
+Either another instance of $0 is running, or it was previously interrupted.
+Please examine ${tmpfile} to see if it should be moved onto ${file}.
+EOF
+        exit 1
+fi
+
+# this is supposed to be reliable, not pretty
+for i
+do
+	grep -v "^${i}$" $tmpfile > $otmpfile || true
+	mv $otmpfile $tmpfile
+done
+
+chmod --reference=$file $tmpfile
+chown --reference=$file $tmpfile
+
+mv $tmpfile $file
+
+trap "" EXIT
+exit 0