Q:

Document compiling when compiling with macos and overleaf, but fails when compiling with linux based system

I am unable to compile a quiz document specifically only on linux machines. My code looks like: 
%% Language and font encodings
\usepackage[english]{babel}
\usepackage[utf8x]{inputenc}
\usepackage[T1]{fontenc}

%% Sets page size and margins
\usepackage[a4paper,margin=1cm]{geometry}

%% Useful packages
\usepackage{amsmath}
\usepackage{graphicx}
\usepackage{paralist}
\setlength\FrameSep{4pt}

\begin{document}
\vspace{5mm}
\begin{center}
\fbox{\fbox{\parbox{2in}{\centering
Quiz 1}}}

\vspace{5mm}

\makebox[\textwidth]{Name:\enspace\hrulefill}
\vspace{5mm}
\makebox[\textwidth]{Section:\enspace\hrulefill}
%questions being here

\begin{questions}
    \question[2]{Sample Question}
    \begin{framed}
        \begin{compactenum}[a.]
        \item option 1.
        \item Option 2.
        \item option 3.
        \item none of the above.
        \end{compactenum}
\end{framed}
\end{questions}
\end{center}
\end{document} 

This code is compiling on mac systems as well as online services like overleaf, but fails on linux systems. The error file looks like
This is pdfTeX, Version 3.14159265-2.6-1.40.18 (TeX Live 2017/Debian) (preloaded format=latex)
 restricted \write18 enabled.
entering extended mode
(./newQuizCopy.tex
LaTeX2e <2017-04-15>
Babel <3.18> and hyphenation patterns for 84 language(s) loaded.
(/usr/share/texlive/texmf-dist/tex/latex/exam/exam.cls
Document Class: exam 2017/12/17 Version 2.603 by Philip Hirschhorn
(/usr/share/texlive/texmf-dist/tex/latex/base/ifthen.sty)
(/usr/share/texlive/texmf-dist/tex/latex/base/article.cls
Document Class: article 2014/09/29 v1.4h Standard LaTeX document class
(/usr/share/texlive/texmf-dist/tex/latex/base/size10.clo)))
(/usr/share/texlive/texmf-dist/tex/generic/babel/babel.sty
(/usr/share/texlive/texmf-dist/tex/generic/babel/switch.def)
(/usr/share/texlive/texmf-dist/tex/generic/babel-english/english.ldf
(/usr/share/texlive/texmf-dist/tex/generic/babel/babel.def
(/usr/share/texlive/texmf-dist/tex/generic/babel/txtbabel.def))))
(/usr/share/texlive/texmf-dist/tex/latex/base/inputenc.sty
(/usr/share/texlive/texmf-dist/tex/latex/ucs/utf8x.def))
(/usr/share/texlive/texmf-dist/tex/latex/ucs/ucs.sty
(/usr/share/texlive/texmf-dist/tex/latex/ucs/data/uni-global.def))
(/usr/share/texlive/texmf-dist/tex/latex/base/fontenc.sty
(/usr/share/texlive/texmf-dist/tex/latex/base/t1enc.def))
(/usr/share/texlive/texmf-dist/tex/latex/geometry/geometry.sty
(/usr/share/texlive/texmf-dist/tex/latex/graphics/keyval.sty)
(/usr/share/texlive/texmf-dist/tex/generic/oberdiek/ifpdf.sty)
(/usr/share/texlive/texmf-dist/tex/generic/oberdiek/ifvtex.sty)
(/usr/share/texlive/texmf-dist/tex/generic/ifxetex/ifxetex.sty))
(/usr/share/texlive/texmf-dist/tex/latex/amsmath/amsmath.sty
For additional information on amsmath, use the `?' option.
(/usr/share/texlive/texmf-dist/tex/latex/amsmath/amstext.sty
(/usr/share/texlive/texmf-dist/tex/latex/amsmath/amsgen.sty))
(/usr/share/texlive/texmf-dist/tex/latex/amsmath/amsbsy.sty)
(/usr/share/texlive/texmf-dist/tex/latex/amsmath/amsopn.sty))
(/usr/share/texlive/texmf-dist/tex/latex/graphics/graphicx.sty
(/usr/share/texlive/texmf-dist/tex/latex/graphics/graphics.sty
(/usr/share/texlive/texmf-dist/tex/latex/graphics/trig.sty)
(/usr/share/texlive/texmf-dist/tex/latex/graphics-cfg/graphics.cfg)
(/usr/share/texlive/texmf-dist/tex/latex/graphics-def/dvips.def)))
(/usr/share/texlive/texmf-dist/tex/latex/paralist/paralist.sty)

! LaTeX Error: Missing \begin{document}.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.

l.15 \setlength\FrameSep{4pt}

And the log file displays
This is pdfTeX, Version 3.14159265-2.6-1.40.18 (TeX Live 2017/Debian) (preloaded format=latex 2018.10.31)  27 FEB 2019 23:07
entering extended mode
 restricted \write18 enabled.
 %&-line parsing enabled.
**newQuizCopy.tex
(./newQuizCopy.tex
LaTeX2e <2017-04-15>
Babel <3.18> and hyphenation patterns for 84 language(s) loaded.
(/usr/share/texlive/texmf-dist/tex/latex/exam/exam.cls
Document Class: exam 2017/12/17 Version 2.603 by Philip Hirschhorn
(/usr/share/texlive/texmf-dist/tex/latex/base/ifthen.sty
Package: ifthen 2014/09/29 v1.1c Standard LaTeX ifthen package (DPC)
)
(/usr/share/texlive/texmf-dist/tex/latex/base/article.cls
Document Class: article 2014/09/29 v1.4h Standard LaTeX document class
(/usr/share/texlive/texmf-dist/tex/latex/base/size10.clo
File: size10.clo 2014/09/29 v1.4h Standard LaTeX file (size option)
)
\c@part=\count79
\c@section=\count80
\c@subsection=\count81
\c@subsubsection=\count82
\c@paragraph=\count83
\c@subparagraph=\count84
\c@figure=\count85
\c@table=\count86
\abovecaptionskip=\skip41
\belowcaptionskip=\skip42
\bibindent=\dimen102
)
\@extrawidth=\skip43
\@rightmargin=\skip44
\@extrahead=\skip45
\@extrafoot=\skip46
\run@exhd=\skip47
\fp@exhd=\skip48
\run@exft=\skip49
\fp@exft=\skip50
\covrun@exhd=\skip51
\covfp@exhd=\skip52
\covrun@exft=\skip53
\covfp@exft=\skip54
\c@num@coverpages=\count87
\c@latest@ques=\count88
\c@ques@end=\count89
\c@last@object=\count90
\c@incmp@ques=\count91
\c@next@ques=\count92
\c@next@page=\count93
\c@tmp@hlfcntr=\count94
\c@ifpos@cntr=\count95
\c@question=\count96
\c@partno=\count97
\c@subpart=\count98
\c@subsubpart=\count99
\c@choice=\count100
\c@numpoints=\count101
\c@numbonuspoints=\count102
\c@pointsof@thisquestion=\count103
\c@bonuspointsof@thisquestion=\count104
\c@numquestions=\count105
\c@numparts=\count106
\c@numsubparts=\count107
\c@numsubsubparts=\count108
\c@Curr@Page=\count109
\c@@pagepoints=\count110
\c@@pagebonuspoints=\count111
\c@pageof@pagepoints=\count112
\c@pageof@pagebonuspoints=\count113
\c@latest@points=\count114
\c@latest@bonuspoints=\count115
\pageinfo@commands=\toks14
\temp@toks=\toks15
\pagepoint@commands=\toks16
\point@toks=\toks17
\c@ques@object=\count116
\marginpointssep=\skip55
\rightpointsmargin=\skip56
\choice@toks=\toks18
\answerlinelength=\skip57
\answerskip=\skip58
\answerclearance=\skip59
\fillinlinelength=\skip60
\linefillheight=\skip61
\linefillthickness=\skip62
\dottedlinefillheight=\skip63
\gridsize=\skip64
\gridlinewidth=\skip65
\minboxheight=\skip66
\c@@iterator=\count117
\@cellwidth=\skip67
\c@tbl@points=\count118
\c@tbl@bonuspoints=\count119
\c@pq@index=\count120
\c@pq@index@pts=\count121
\c@pq@index@bpts=\count122
\c@num@cols=\count123
\c@num@rows=\count124
\c@current@row=\count125
\c@cols@done=\count126
\exam@box=\box26
\saved@totalleftmargin=\dimen103
\@sollistdepth=\count127
\exam@FrameRule=\dimen104
\exam@FrameSep=\dimen105
)
(/usr/share/texlive/texmf-dist/tex/generic/babel/babel.sty
Package: babel 2018/02/14 3.18 The Babel package

(/usr/share/texlive/texmf-dist/tex/generic/babel/switch.def
File: switch.def 2018/02/14 3.18 Babel switching mechanism
)
(/usr/share/texlive/texmf-dist/tex/generic/babel-english/english.ldf
Language: english 2017/06/06 v3.3r English support from the babel system

(/usr/share/texlive/texmf-dist/tex/generic/babel/babel.def
File: babel.def 2018/02/14 3.18 Babel common definitions
\babel@savecnt=\count128
\U@D=\dimen106

(/usr/share/texlive/texmf-dist/tex/generic/babel/txtbabel.def)
\bbl@dirlevel=\count129
)
\l@canadian = a dialect from \language\l@american 
\l@australian = a dialect from \language\l@british 
\l@newzealand = a dialect from \language\l@british 
))
(/usr/share/texlive/texmf-dist/tex/latex/base/inputenc.sty
Package: inputenc 2015/03/17 v1.2c Input encoding file
\inpenc@prehook=\toks19
\inpenc@posthook=\toks20

(/usr/share/texlive/texmf-dist/tex/latex/ucs/utf8x.def
File: utf8x.def 2004/10/17 UCS: Input encoding UTF-8
))
(/usr/share/texlive/texmf-dist/tex/latex/ucs/ucs.sty
Package: ucs 2013/05/11 v2.2 UCS: Unicode input support

(/usr/share/texlive/texmf-dist/tex/latex/ucs/data/uni-global.def
File: uni-global.def 2013/05/13 UCS: Unicode global data
)
\uc@secondtry=\count130
\uc@combtoks=\toks21
\uc@combtoksb=\toks22
\uc@temptokena=\toks23
)
(/usr/share/texlive/texmf-dist/tex/latex/base/fontenc.sty
Package: fontenc 2017/04/05 v2.0i Standard LaTeX package

(/usr/share/texlive/texmf-dist/tex/latex/base/t1enc.def
File: t1enc.def 2017/04/05 v2.0i Standard LaTeX file
LaTeX Font Info:    Redeclaring font encoding T1 on input line 48.
))
(/usr/share/texlive/texmf-dist/tex/latex/geometry/geometry.sty
Package: geometry 2010/09/12 v5.6 Page Geometry

(/usr/share/texlive/texmf-dist/tex/latex/graphics/keyval.sty
Package: keyval 2014/10/28 v1.15 key=value parser (DPC)
\KV@toks@=\toks24
)
(/usr/share/texlive/texmf-dist/tex/generic/oberdiek/ifpdf.sty
Package: ifpdf 2017/03/15 v3.2 Provides the ifpdf switch
)
(/usr/share/texlive/texmf-dist/tex/generic/oberdiek/ifvtex.sty
Package: ifvtex 2016/05/16 v1.6 Detect VTeX and its facilities (HO)
Package ifvtex Info: VTeX not detected.
)
(/usr/share/texlive/texmf-dist/tex/generic/ifxetex/ifxetex.sty
Package: ifxetex 2010/09/12 v0.6 Provides ifxetex conditional
)
\Gm@cnth=\count131
\Gm@cntv=\count132
\c@Gm@tempcnt=\count133
\Gm@bindingoffset=\dimen107
\Gm@wd@mp=\dimen108
\Gm@odd@mp=\dimen109
\Gm@even@mp=\dimen110
\Gm@layoutwidth=\dimen111
\Gm@layoutheight=\dimen112
\Gm@layouthoffset=\dimen113
\Gm@layoutvoffset=\dimen114
\Gm@dimlist=\toks25
)
(/usr/share/texlive/texmf-dist/tex/latex/amsmath/amsmath.sty
Package: amsmath 2017/09/02 v2.17a AMS math features
\@mathmargin=\skip68

For additional information on amsmath, use the `?' option.
(/usr/share/texlive/texmf-dist/tex/latex/amsmath/amstext.sty
Package: amstext 2000/06/29 v2.01 AMS text

(/usr/share/texlive/texmf-dist/tex/latex/amsmath/amsgen.sty
File: amsgen.sty 1999/11/30 v2.0 generic functions
\@emptytoks=\toks26
\ex@=\dimen115
))
(/usr/share/texlive/texmf-dist/tex/latex/amsmath/amsbsy.sty
Package: amsbsy 1999/11/29 v1.2d Bold Symbols
\pmbraise@=\dimen116
)
(/usr/share/texlive/texmf-dist/tex/latex/amsmath/amsopn.sty
Package: amsopn 2016/03/08 v2.02 operator names
)
\inf@bad=\count134
LaTeX Info: Redefining \frac on input line 213.
\uproot@=\count135
\leftroot@=\count136
LaTeX Info: Redefining \overline on input line 375.
\classnum@=\count137
\DOTSCASE@=\count138
LaTeX Info: Redefining \ldots on input line 472.
LaTeX Info: Redefining \dots on input line 475.
LaTeX Info: Redefining \cdots on input line 596.
\Mathstrutbox@=\box27
\strutbox@=\box28
\big@size=\dimen117
LaTeX Font Info:    Redeclaring font encoding OML on input line 712.
LaTeX Font Info:    Redeclaring font encoding OMS on input line 713.
\macc@depth=\count139
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\andhelp@=\toks28
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\@envbody=\toks29
\multlinegap=\skip69
\multlinetaggap=\skip70
\mathdisplay@stack=\toks30
LaTeX Info: Redefining \[ on input line 2817.
LaTeX Info: Redefining \] on input line 2818.
)
(/usr/share/texlive/texmf-dist/tex/latex/graphics/graphicx.sty
Package: graphicx 2017/06/01 v1.1a Enhanced LaTeX Graphics (DPC,SPQR)

(/usr/share/texlive/texmf-dist/tex/latex/graphics/graphics.sty
Package: graphics 2017/06/25 v1.2c Standard LaTeX Graphics (DPC,SPQR)

(/usr/share/texlive/texmf-dist/tex/latex/graphics/trig.sty
Package: trig 2016/01/03 v1.10 sin cos tan (DPC)
)
(/usr/share/texlive/texmf-dist/tex/latex/graphics-cfg/graphics.cfg
File: graphics.cfg 2016/06/04 v1.11 sample graphics configuration
)
Package graphics Info: Driver file: dvips.def on input line 99.

(/usr/share/texlive/texmf-dist/tex/latex/graphics-def/dvips.def
File: dvips.def 2017/06/20 v3.1d Graphics/color driver for dvips
))
\Gin@req@height=\dimen124
\Gin@req@width=\dimen125
)
(/usr/share/texlive/texmf-dist/tex/latex/paralist/paralist.sty
Package: paralist 2017/01/22 v2.7 Extended list environments
\pltopsep=\skip71
\plpartopsep=\skip72
\plitemsep=\skip73
\plparsep=\skip74
\pl@lab=\toks31
)

! LaTeX Error: Missing \begin{document}.

See the LaTeX manual or LaTeX Companion for explanation.
Type  H <return>  for immediate help.
 ...                                              

l.15 \setlength\FrameSep{4pt}

? X

Here is how much of TeX's memory you used:
 3770 strings out of 492983
 50639 string characters out of 6134921
 140557 words of memory out of 5000000
 7327 multiletter control sequences out of 15000+600000
 4403 words of font info for 15 fonts, out of 8000000 for 9000
 1141 hyphenation exceptions out of 8191
 29i,0n,32p,335b,37s stack positions out of 5000i,500n,10000p,200000b,80000s
No pages of output.

I am new to LaTeX so please help me here. 

A:

Well you did not add in your given code that you are using class exam. So I added \documentclass{exam} in the following MWE. If you are using special, for the issue relevant options for class exam please add them to your question.
Compiling then returns the error

! Undefined control sequence.
<argument> \FrameSep 

l.17 \setlength\FrameSep{4pt}

That means you missed to call package framed in your preamble with 
\usepackage{framed} 

The following complete MWE 
\documentclass{exam} % <================================================
%% Language and font encodings
\usepackage[english]{babel}
\usepackage[utf8x]{inputenc}
\usepackage[T1]{fontenc}

%% Sets page size and margins
\usepackage[a4paper,margin=1cm]{geometry}

%% Useful packages
\usepackage{amsmath}
\usepackage{graphicx}
\usepackage{paralist}

\usepackage{framed} % <=================================================
\setlength\FrameSep{4pt}

\begin{document}
\vspace{5mm}
\begin{center}
\fbox{\fbox{\parbox{2in}{\centering
Quiz 1}}}

\vspace{5mm}

\makebox[\textwidth]{Name:\enspace\hrulefill}
\vspace{5mm}
\makebox[\textwidth]{Section:\enspace\hrulefill}
%questions being here

\begin{questions}
    \question[2]{Sample Question}
    \begin{framed}
        \begin{compactenum}[a.]
        \item option 1.
        \item Option 2.
        \item option 3.
        \item none of the above.
        \end{compactenum}
\end{framed}
\end{questions}
\end{center}
\end{document} 

results in

