I am using various stdlib functions like srand(), etc. I have the line #include

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Asked: May 24, 20262026-05-24T07:01:29+00:00 2026-05-24T07:01:29+00:00

I am using various stdlib functions like srand(), etc. I have the line #include

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I am using various stdlib functions like srand(), etc. I have the line

#include <stdlib.h>

at the top of my code.

I entered this on the command line:

# find / -name stdlib.h

find: `/home/dmurvihill/.gvfs: permission denied
/usr/include/stdlib.h
/usr/include/bits/stdlib.h

So, stdlib.h is clearly in /usr/include.

My preprocessor:

# gcc -print-prog-name=cc1

/usr/libexec/gcc/x86_64-redhat-linux/4.5.1/cc1

My preprocessor’s default search path:

# /usr/libexec/gcc/x86_64-redhat-linux/4.5.1/cc1 -v

ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/4.5.1/include-fixed"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/4.5.1/../../../../x86_64-redhat-linux/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/local/include
/usr/lib/gcc/x86_64-redhat-linux/4.5.1/include
/usr/include
End of search list.

So, stdlib.h is clearly in /usr/include, which is most definitely supposed to be searched by my preprocessor, but I still get this error!

/path/to/cpa_sample_code_main.c:15:20: fatal error: stdlib.h: No such file or directory
compilation terminated

Update

A program I wrote to test this code:

#include <stdio.h>
#include <stdlib.h>
#include <linux/time.h>

int main()
{
    printf("Hello, World!\n");
    printf("Getting time...\n");
    time_t seconds;
    time(&seconds);
    printf("Seeding generator...\n");
    srand((unsigned int)seconds);
    printf("Getting random number...\n");
    int value = rand();
    printf("It is %d!",value);
    printf("Goodbye, cruel world!");
    return 0;
}

The command

gcc -H -v -fsyntax-only stdlib_test.c

output

Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.5.1/lto-wrapper
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --enable-languages=c,c++,objc,obj-c++,java,fortran,ada,lto --enable-plugin --enable-java-awt=gtk --disable-dssi --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib --with-ppl --with-cloog --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
gcc version 4.5.1 20100924 (Red Hat 4.5.1-4) (GCC) 
COLLECT_GCC_OPTIONS='-H' '-v' '-fsyntax-only' '-mtune=generic' '-march=x86-64'
 /usr/libexec/gcc/x86_64-redhat-linux/4.5.1/cc1 -quiet -v -H /CRF_Verify/stdlib_test.c -quiet -dumpbase stdlib_test.c -mtune=generic -march=x86-64 -auxbase stdlib_test -version -fsyntax-only -o /dev/null
GNU C (GCC) version 4.5.1 20100924 (Red Hat 4.5.1-4) (x86_64-redhat-linux)
    compiled by GNU C version 4.5.1 20100924 (Red Hat 4.5.1-4), GMP version 4.3.1, MPFR version 2.4.2, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/4.5.1/include-fixed"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/4.5.1/../../../../x86_64-redhat-linux/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/include
 /usr/lib/gcc/x86_64-redhat-linux/4.5.1/include
 /usr/include
End of search list.
GNU C (GCC) version 4.5.1 20100924 (Red Hat 4.5.1-4) (x86_64-redhat-linux)
    compiled by GNU C version 4.5.1 20100924 (Red Hat 4.5.1-4), GMP version 4.3.1, MPFR version 2.4.2, MPC version 0.8.1
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: ea394b69293dd698607206e8e43d607e
. /usr/include/stdio.h
.. /usr/include/features.h
... /usr/include/sys/cdefs.h
.... /usr/include/bits/wordsize.h
... /usr/include/gnu/stubs.h
.... /usr/include/bits/wordsize.h
.... /usr/include/gnu/stubs-64.h
.. /usr/lib/gcc/x86_64-redhat-linux/4.5.1/include/stddef.h
.. /usr/include/bits/types.h
... /usr/include/bits/wordsize.h
... /usr/include/bits/typesizes.h
.. /usr/include/libio.h
... /usr/include/_G_config.h
.... /usr/lib/gcc/x86_64-redhat-linux/4.5.1/include/stddef.h
.... /usr/include/wchar.h
... /usr/lib/gcc/x86_64-redhat-linux/4.5.1/include/stdarg.h
.. /usr/include/bits/stdio_lim.h
.. /usr/include/bits/sys_errlist.h
. /usr/include/stdlib.h
.. /usr/lib/gcc/x86_64-redhat-linux/4.5.1/include/stddef.h
.. /usr/include/bits/waitflags.h
.. /usr/include/bits/waitstatus.h
... /usr/include/endian.h
.... /usr/include/bits/endian.h
.... /usr/include/bits/byteswap.h
..... /usr/include/bits/wordsize.h
.. /usr/include/sys/types.h
... /usr/include/time.h
... /usr/lib/gcc/x86_64-redhat-linux/4.5.1/include/stddef.h
... /usr/include/sys/select.h
.... /usr/include/bits/select.h
..... /usr/include/bits/wordsize.h
.... /usr/include/bits/sigset.h
.... /usr/include/time.h
.... /usr/include/bits/time.h
... /usr/include/sys/sysmacros.h
... /usr/include/bits/pthreadtypes.h
.... /usr/include/bits/wordsize.h
.. /usr/include/alloca.h
... /usr/lib/gcc/x86_64-redhat-linux/4.5.1/include/stddef.h
. /usr/include/linux/time.h
.. /usr/include/linux/types.h
... /usr/include/asm/types.h
.... /usr/include/asm-generic/types.h
..... /usr/include/asm-generic/int-ll64.h
...... /usr/include/asm/bitsperlong.h
....... /usr/include/asm-generic/bitsperlong.h
... /usr/include/linux/posix_types.h
.... /usr/include/linux/stddef.h
.... /usr/include/asm/posix_types.h
..... /usr/include/asm/posix_types_64.h
In file included from /CRF_Verify/stdlib_test.c:3:0:
/usr/include/linux/time.h:9:8: error: redefinition of ‘struct timespec’
/usr/include/time.h:120:8: note: originally defined here
/usr/include/linux/time.h:15:8: error: redefinition of ‘struct timeval’
/usr/include/bits/time.h:75:8: note: originally defined here
Multiple include guards may be useful for:
/usr/include/asm/posix_types.h
/usr/include/bits/byteswap.h
/usr/include/bits/endian.h
/usr/include/bits/select.h
/usr/include/bits/sigset.h
/usr/include/bits/stdio_lim.h
/usr/include/bits/sys_errlist.h
/usr/include/bits/time.h
/usr/include/bits/typesizes.h
/usr/include/bits/waitflags.h
/usr/include/bits/waitstatus.h
/usr/include/gnu/stubs-64.h
/usr/include/gnu/stubs.h
/usr/include/wchar.h

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1 Answer

Editorial Team · Answer 1 · 2026-05-24T07:01:32+00:00

Your error appears to stem from including linux/time.h when also trying to include stdlib.h. linux/time.h is a kernel header and should only be used in kernel code. stdlib.h is a user-land function and should only be used in user programs. If you notice the error you get:

/usr/include/linux/time.h:12: error: redefinition of 'struct timespec'
/usr/include/linux/time.h:18: error: redefinition of 'struct timeval'

you can see that you are getting an error related to this. As seen in your long trace, this is because stdlib.h is including time.h (the one in /usr/include, not /usr/include/linux). I imagine that this is the real cause of the error you see about not finding stdlib.h (although I cannot imagine the details of how the errors are occurring the way they are).

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