compilation error fatal error: sys\types.h: No such file or directory #include <sys\types.h>
<p>I've looked and looked for a solution to this.  Sure there are these links that suggest one thing or another:</p>

<p><a href="https://stackoverflow.com/questions/33819808/error-sys-types-h-no-such-directory-found">Error :sys/types.h No such directory found</a></p>

<p><a href="https://stackoverflow.com/questions/16496635/fatal-error-sys-socket-h-no-such-file-or-directory-on-32bit">fatal error: sys/socket.h: No such file or directory on 32bit</a></p>

<p><a href="https://stackoverflow.com/questions/33819808/error-sys-types-h-no-such-directory-found">Error :sys/types.h No such directory found</a></p>

<p>and other similar links too.  </p>

<p>Let me give you the error, the relevant Makefile statements and show you my directory structure for include.</p>

<p><strong>The Error</strong></p>

<pre><code>gcc -o obj/nmlflpth.o -std=c99 -Ilarc/include -Ilarc/modules/include -Ilarc/milesup -Ilarc/pftk -Ilarc/npsol -Ilarc/src -Ilarc/uih -Ilarc/util -Ilarc/uopt -Ilarc/pgm -Ilarc/navlrc -Ilarc/modules/production/common -Ilarc/src_test -Ilarc/gtest/include -c -O2 larc/uih/nmlflpth.c
larc/uih/nmlflpth.c:48:23: fatal error: sys\types.h: No such file or directory
#include &lt;sys\types.h&gt;
</code></pre>

<p><strong>The Relevant Makefile Statements</strong></p>

<pre><code># list of all dirs with compilable C, C++ and F77 code
dirs    :=  larc/milesup \
            larc/pftk \
            larc/npsol \
            larc/src \
            larc/uih \
            larc/util \
            larc/uopt \
            larc/pgm \
            larc/navlrc \
            larc/modules/production/common

# list of dirs with include/header files
idirs   := larc/include larc/modules/include
idirs   += $(dirs)
idirs   += larc/gtest/include
ipaths  := $(addprefix -I, $(idirs))
cflags  := -std=c99 $(ipaths)
optflag := -O2

cdefines:= -DVERSION_BUILD_DATE="\"$(shell date)\"" \
       -DVERSION_VENDOR="\"$(VENDOR)\"" \
       -DVERSION_OSTYPE="\"$(OSTYPE)\"" \
       -DVERSION_HOST="\"$(HOST)\"" \
       -DVERSION_USER_NAME="\"$(USER)\"" \
       -DVERSION_VIEW_NAME="\"NONCLEARCASE\""   

$(cobjs): obj/%.o: %.c
    # $(CC) -o $@ $(cflags) -c $(optflag) $&lt;
    @ -mkdir -p obj/
    @ $(CC) -o $@ $(cflags) $(cdefines) $(ipaths) -c $(optflag) $&lt;
</code></pre>

<p>note that:
    @ $(CC) -o $@ $(cflags) $(cdefines) $(ipaths) -c $(optflag) $&lt;
Really only seems to output the following 
    @ $(CC) -o $@ $(cflags) -c $(optflag) $&lt;</p>

<p>why?  I have no clue. </p>

<p><strong>Include folders for sys/types.h</strong></p>

<p>So this is what gcc is looking for:</p>

<pre><code>$echo "#include &lt;sys/types.h&gt;" | gcc -E -x c - | grep types
# 1 "/usr/include/x86_64-linux-gnu/sys/types.h" 1 3 4
# 25 "/usr/include/x86_64-linux-gnu/sys/types.h" 3 4
# 26 "/usr/include/x86_64-linux-gnu/sys/types.h" 2 3 4
# 1 "/usr/include/x86_64-linux-gnu/bits/types.h" 1 3 4
# 27 "/usr/include/x86_64-linux-gnu/bits/types.h" 3 4
# 28 "/usr/include/x86_64-linux-gnu/bits/types.h" 2 3 4
# 121 "/usr/include/x86_64-linux-gnu/bits/types.h" 3 4
# 1 "/usr/include/x86_64-linux-gnu/bits/typesizes.h" 1 3 4
# 122 "/usr/include/x86_64-linux-gnu/bits/types.h" 2 3 4
# 30 "/usr/include/x86_64-linux-gnu/sys/types.h" 2 3 4
# 60 "/usr/include/x86_64-linux-gnu/sys/types.h" 3 4
# 98 "/usr/include/x86_64-linux-gnu/sys/types.h" 3 4
# 132 "/usr/include/x86_64-linux-gnu/sys/types.h" 3 4
# 133 "/usr/include/x86_64-linux-gnu/sys/types.h" 2 3 4
# 146 "/usr/include/x86_64-linux-gnu/sys/types.h" 3 4
# 147 "/usr/include/x86_64-linux-gnu/sys/types.h" 2 3 4
# 194 "/usr/include/x86_64-linux-gnu/sys/types.h" 3 4
# 216 "/usr/include/x86_64-linux-gnu/sys/types.h" 3 4
# 217 "/usr/include/x86_64-linux-gnu/sys/types.h" 2 3 4
# 220 "/usr/include/x86_64-linux-gnu/sys/types.h" 2 3 4
# 223 "/usr/include/x86_64-linux-gnu/sys/types.h" 2 3 4
# 270 "/usr/include/x86_64-linux-gnu/sys/types.h" 3 4
# 1 "/usr/include/x86_64-linux-gnu/bits/pthreadtypes.h" 1 3 4
# 21 "/usr/include/x86_64-linux-gnu/bits/pthreadtypes.h" 3 4
# 22 "/usr/include/x86_64-linux-gnu/bits/pthreadtypes.h" 2 3 4
# 60 "/usr/include/x86_64-linux-gnu/bits/pthreadtypes.h" 3 4
# 90 "/usr/include/x86_64-linux-gnu/bits/pthreadtypes.h" 3 4
# 124 "/usr/include/x86_64-linux-gnu/bits/pthreadtypes.h" 3 4
# 211 "/usr/include/x86_64-linux-gnu/bits/pthreadtypes.h" 3 4
# 271 "/usr/include/x86_64-linux-gnu/sys/types.h" 2 3 4
</code></pre>

<p>I have the following folder content for types.h:</p>

<pre><code>$ls /usr/include/x86_64-linux-gnu/sys |grep types.h
bitypes.h
types.h
</code></pre>

<p>and </p>

<pre><code>ls /usr/include/sys |grep types.h
bitypes.h
types.h
</code></pre>

<p>from debian package:</p>

<pre><code>$ dpkg -S /usr/include/sys/types.h 
libc6-dev-amd64: /usr/include/sys/types.h
$ dpkg -S /usr/include/x86_64-linux-gnu/sys/types.h 
libc6-dev:amd64: /usr/include/x86_64-linux-gnu/sys/types.h
</code></pre>

<p>Any help on this is greatly appreciated.  Thanks!</p>