libpq-fe.h: No such file or directory (Ubuntu 20)

Question

Compiling in Ubuntu 20.04.4 LTS, g++ returns

libpq-fe.h is not found

The system already has it installed (sudo apt-get install libpq-dev) in

/usr/include/postgresql/libpq-fe.h

I tried to set the compilation path with option -I/usr/include/postgresql but it still claims about missing libpq-fe.h

I manually ran the make command for a single target with -I/usr/include/postgresql and it worked. I guess I need to review the Makefile. Thanks — alboforlizo, Mar 30 '23 at 16:37
@alboforlizo I just tried with -I after having the same issue with no luck. Is your above comment not accurate? — Cogito Ergo Sum, Mar 30 '23 at 21:13
-I/usr/include/postgresql solves the compiling issues but not linking! Try manually from command line, this compiles ok: g++ -c *.cpp -I/usr/include/postgresql -lm -lcrypto -lpq -lpthread — alboforlizo, Mar 31 '23 at 13:01
/usr/bin/ld...undefined reference...I have now a linking issue — alboforlizo, Mar 31 '23 at 13:18
Linking issue solved by this command: g++ -L/usr/lib/x86_64-linux-gnu -o test *.o -lm -lcrypto -lpq -lpthread — alboforlizo, Mar 31 '23 at 13:42

alboforlizo · Accepted Answer · 2023-03-31T15:48:10.397

As you can see, I had to manually insert both -I/usr/include/postgresql and -L/usr/lib/x86_64-linux-gnu to make -lpq (libpq) work with g++ in Ubuntu:

TARGET = prog
LIBS = -lm -lcrypto -lpq -lpthread
CC = g++
CFLAGS = -g -Wall
ODIR = ../src

.PHONY: default all clean

default: $(TARGET)
all: default

OBJS = $(patsubst %.cpp, %.o, $(wildcard ../src/*.cpp))
HEADERS = $(wildcard ../src/*.h)

all: $(TARGET)
$(TARGET): $(OBJS)
        $(CC) -L/usr/lib/x86_64-linux-gnu -o $@ $^ $(LIBS)
$(ODIR)/%.o: $(ODIR)/%.cpp
        $(CC) $(CFLAGS) -I/usr/include/postgresql -c $< -o $@

clean:
        -rm -f ../src/*.o
        -rm -f $(TARGET)

In case of "cannot find -lpq" with libpq.so.5 already in /usr/lib/x86_64-linux-gnu:

sudo ln -s /usr/lib/x86_64-linux-gnu/libpq.so.5 /usr/lib/x86_64-linux-gnu/libpq.so

libpq-fe.h: No such file or directory (Ubuntu 20)

1 Answers1