Can't write in Arabic: Package babel Error: Language definition file main=arabic.ldf not found. \ProcessOptions*

Question

I am using Ubuntu system. I use TexStudio editor which uses TeX Live 2017/Debian and the editor's compiler is configured to be pdflatex.

My main document is in English language. But I need to write some Arabic text in some lines. I use arabtex as in the following minimal script:

\PassOptionsToPackage{main=arabic}{babel}
\documentclass[a4paper,twoside]{ociamthesis}
\fancyfoot[C]{\emph{DRAFT Printed on \today}}  
\correctionstrue
\newcommand*{\bibtitle}{References}

%---------- START FOR ARABIC ----------------------------
\usepackage{arabtex}
\usepackage[utf8]{inputenc}
\usepackage[LFE,LAE]{fontenc}
%---------- END FOR ARABIC ----------------------------

\title{Suitably impressive thesis title}
\author{Your Name}
\college{Your College}
\degree{Doctor of Philosophy}
\degreedate{Michaelmas 2014}

\begin{document}

\setlength{\textbaselineskip}{22pt plus2pt}
\setlength{\frontmatterbaselineskip}{17pt plus1pt minus1pt}
\setlength{\baselineskip}{\textbaselineskip}
\setcounter{secnumdepth}{2}
\setcounter{tocdepth}{2}

\begin{romanpages}
\maketitle

\begin{acknowledgements}
    \begin{otherlanguage}{arabic}
        سلام 
    \end{otherlanguage}
\end{acknowledgements}

\begin{abstract}
    My abstract here in English.
\end{abstract}

\end{romanpages}

\end{document}

But I am getting the following errors when I compile the document:

Package babel Error: Language definition file main=arabic.ldf not found. \ProcessOptions*

Package babel Error: Unknown language `arabic'. Either you have(babel) install it or just rerun the file, respectively. \begin{otherlanguage}{arabic}

\begin{alwayssingle} on input line 37 ended by \end{abstract}. \end{abstract}

\begin{abstract} on input line 37 ended by \end{romanpages}. \end{romanpages}

\begin{romanpages} on input line 28 ended by \end{document}. \end{document}

Font shape `LAE/lmr/m/n' undefined(Font) using `LAE/cmr/m/n' instead

Font shape `LAE/lmr/bx/n' undefined(Font) using `LAE/lmr/m/n' instead

Font shape `LAE/lmr/m/it' undefined(Font) using `LAE/lmr/m/n' instead

Some font shapes were not available, defaults substituted.

Can anyone help me figure out how to insert some Arabic lines of text (e.g. in the dedication or acknowledgement parts) in an English latex document?

Answer 1

The arabic.ldf of babel (and also the arabtex package) make many changes to various commands which can clash in various places (e.g. in the combination of minitoc and microtype). Both are also rather old and haven't been changed since many years as most people use xelatex or lualatex for such scripts.

If you need arabic only for a few works and want to stick to pdflatex, you should consider to avoid to load arabic.ldf and only manually switch the font and the direction:

\documentclass{book}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage[LAE,T1]{fontenc}

\TeXXeTstate=1
\begin{document}
Some arabic

\makeatletter
\bgroup\beginR\raggedleft\fontencoding{LAE}\selectfont سلام\endR\par\egroup

\end{document}

Answer 2

First off, you don't want the main language is Arabic, do you?

Second, arabtex does several redefinitions that clash with the document class; leave it out.

You also need to restore a Latin output encoding.

\PassOptionsToPackage{arabic}{babel}% <----  CHANGE HERE
\documentclass[a4paper,twoside]{ociamthesis}

\fancyfoot[C]{\emph{DRAFT Printed on \today}}  
\correctionstrue
\newcommand*{\bibtitle}{References}

%---------- START FOR ARABIC ----------------------------
%\usepackage{arabtex}% <----  CHANGE HERE
\usepackage[utf8]{inputenc}
\usepackage[LFE,LAE,T1]{fontenc}% <----  CHANGE HERE
%---------- END FOR ARABIC ----------------------------

\title{Suitably impressive thesis title}
\author{Your Name}
\college{Your College}
\degree{Doctor of Philosophy}
\degreedate{Michaelmas 2014}

\begin{document}

\setlength{\textbaselineskip}{22pt plus2pt}
\setlength{\frontmatterbaselineskip}{17pt plus1pt minus1pt}
\setlength{\baselineskip}{\textbaselineskip}
\setcounter{secnumdepth}{2}
\setcounter{tocdepth}{2}

\begin{romanpages}

\maketitle

\begin{acknowledgements}
    \begin{otherlanguage}{arabic}
        سلام 
    \end{otherlanguage}
\end{acknowledgements}

\begin{abstract}
    My abstract here in English.
\end{abstract}

\end{romanpages}

\end{document}