texexec --help --all gives TeXExec | ["--check check versions"] TeXExec | ["--figures generate overview of figures"] TeXExec | ["--listing list of file content"] TeXExec | ["--make make formats"] TeXExec | ["--modules generate module documentation"] TeXExec | ["--mpgraphic process mp file to stand-alone graphics"] TeXExec | ["--mpstatic process mp/ctx file to stand-alone graphics"] TeXExec | ["--mptex process mp file"] TeXExec | ["--mpxtex process mpx file"] TeXExec | ["--pdfarrange impose pages (booklets)"] TeXExec | ["--pdfcombine combine multiple pages"] TeXExec | ["--pdfcopy copy pages from file(s)"] TeXExec | ["--pdfselect select pages from file(s)"] TeXExec | ["--pdfsplit split file in pages"] TeXExec | ["--pdftrim trim pages from file(s)"] TeXExec | ["--process process file"] TeXExec | [""] TeXExec | ["boolean switches:"] TeXExec | [""] TeXExec | [" allpatterns alpha arrange automprun autopath"] TeXExec | [" autopdf batchmode beta centerpage color"] TeXExec | [" combine draft fast final forcempy"] TeXExec | [" forcetexutil forcexml foxet fullscreen globalfile"] TeXExec | [" keep local markings mkii mkiv"] TeXExec | [" mpyforce noarrange nobackend nobanner noctx"] TeXExec | [" noduplex nomapfiles nompmode nomprun nonstopmode"] TeXExec | [" nooptionfile notparanoid once paranoid pretty"] TeXExec | [" purge purgeall screensaver simplerun synctex"] TeXExec | [" texutil utfbom verbose xpdf"] TeXExec | [""] TeXExec | ["string switches:"] TeXExec | [""] TeXExec | [" addempty arguments backend background backspace"] TeXExec | [" bannerheight bodyfont boxtype combination ctxfile"] TeXExec | [" distribution endcolumn endline engine environments"] TeXExec | [" filename filters input interface language"] TeXExec | [" logfile mainlanguage method mode modefile"] TeXExec | [" modes mpsformats output pages paperformat"] TeXExec | [" paperoffset passon path pdftitle printformat"] TeXExec | [" progname randomseed response result runs"] TeXExec | [" scale selection separation setuppath startcolumn"] TeXExec | [" startline suffix tempdir texformats textwidth"] TeXExec | [" timeout topspace usemodules"] It appears that a `.join` or `.to_s` method is missing somewhere.