Why can my C program run in "git bash", but not in "cmd"?

Question

I wrote a demo using libpq to connect to a PostgreSQL database.

I tried to connect the C file to PostgreSQL by including

#include <libpq-fe.h>

after I added the paths into system variables I:\Program Files\PostgreSQL\12\lib as well as to I:\Program Files\PostgreSQL\12\include and compiled with this command:

gcc -Wall -Wextra -m64 -I "I:\Program Files\PostgreSQL\12\include" -L "I:\Program Files\PostgreSQL\12\lib" testpsql.c -lpq -o testpsql

It first raised three errors, like

libssl-1_1-x64.dll is missing
libintl-8.dll was missing
libcrypto-1_1-x64.dll was missing

After I downloaded these three files and put them into I:\Program Files\PostgreSQL\12\lib , and compiled it again, it shows the error

The application was unable to start correctly (0xc0150002)

when I type testpsql . But if I type ./testpsql on git bash, it works. Anyone can please tell me why?

The code that I used was the first example from here .

Environment: PostgreSQL 12, Windows 10, MinGW64

Answer 1

“Download the DLL files” sounds dangerous. From where?

I would get rid of these files again. Since you probably don't reference these libraries from your code, it must be the dependencies of libpq.dll and are probably found in I:\Program Files\PostgreSQL\12\bin (if you used the EDB installer).

The problem is probably that you the PATH environment variable is different in git bash and in cmd.exe , and in the latter case not all required shared libraries can be found on the PATH . The solution is to change the PATH so that it includes all DLL files the executable requires, not to start copying around files.

It is probably enough to include I:\Program Files\PostgreSQL\12\bin in the PATH . To resolve missing dependencies, use a tool like dependency walker or this replacement .