If you try to install PHP 5.3.6 on Ubuntu by patching sources you will most likely see a lot of error messages similar to the following:
$ ./configure
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
./configure: 490: 5: Bad file descriptor
./configure: 490: :: checking for pthreads_cflags: not found
./configure: 490: 6: Bad file descriptor
./configure: 490: checking for pthreads_cflags... : not found
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
./configure: 492: 5: Bad file descriptor
./configure: 492: :: result: : not found
./configure: 492: 6: Bad file descriptor
./configure: 492: : Permission denied
./configure: 495: 5: Bad file descriptor
./configure: 495: :: checking for pthreads_lib: not found
./configure: 495: 6: Bad file descriptor
./configure: 495: checking for pthreads_lib... : not found
cat: confdefs.h: No such file or directory
./configure: 555: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 555: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 555: ac_fn_c_try_run: not found
./configure: 557: 5: Bad file descriptor
./configure: 557: :: result: : not found
./configure: 557: 6: Bad file descriptor
./configure: 557: : Permission denied
./configure: 633: 5: Bad file descriptor
./configure: 633: :: result: : not found
./configure: 633: 6: Bad file descriptor
./configure: 633: : Permission denied
./configure: 635: 5: Bad file descriptor
./configure: 635: :: result: Configuring SAPI modules: not found
./configure: 635: 6: Bad file descriptor
./configure: 635: Configuring SAPI modules: not found
./configure: 666: 5: Bad file descriptor
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
./configure: 490: 5: Bad file descriptor
./configure: 490: :: checking for pthreads_cflags: not found
./configure: 490: 6: Bad file descriptor
./configure: 490: checking for pthreads_cflags... : not found
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 490: ac_fn_c_try_run: not found
./configure: 492: 5: Bad file descriptor
./configure: 492: :: result: : not found
./configure: 492: 6: Bad file descriptor
./configure: 492: : Permission denied
./configure: 495: 5: Bad file descriptor
./configure: 495: :: checking for pthreads_lib: not found
./configure: 495: 6: Bad file descriptor
./configure: 495: checking for pthreads_lib... : not found
cat: confdefs.h: No such file or directory
./configure: 555: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 555: ac_fn_c_try_run: not found
cat: confdefs.h: No such file or directory
./configure: 555: ac_fn_c_try_run: not found
./configure: 557: 5: Bad file descriptor
./configure: 557: :: result: : not found
./configure: 557: 6: Bad file descriptor
./configure: 557: : Permission denied
./configure: 633: 5: Bad file descriptor
./configure: 633: :: result: : not found
./configure: 633: 6: Bad file descriptor
./configure: 633: : Permission denied
./configure: 635: 5: Bad file descriptor
./configure: 635: :: result: Configuring SAPI modules: not found
./configure: 635: 6: Bad file descriptor
./configure: 635: Configuring SAPI modules: not found
./configure: 666: 5: Bad file descriptor
See what happened when usingĀ buildconf earlier..