+function shellquote(value)
+ return string.format("'%s'", string.gsub(value or "", "'", "'\\''"))
+end
+
+-- for bash, ash and similar shells single-quoted strings are taken
+-- literally except for single quotes (which terminate the string)
+-- (and the exception noted below for dash (-) at the start of a
+-- command line parameter).
+function shellsqescape(value)
+ local res
+ res, _ = string.gsub(value, "'", "'\\''")
+ return res
+end
+
+-- bash, ash and other similar shells interpret a dash (-) at the start
+-- of a command-line parameters as an option indicator regardless of
+-- whether it is inside a single-quoted string. It must be backlash
+-- escaped to resolve this. This requires in some funky special-case
+-- handling. It may actually be a property of the getopt function
+-- rather than the shell proper.
+function shellstartsqescape(value)
+ res, _ = string.gsub(value, "^%-", "\\-")
+ return shellsqescape(res)
+end
+