What does the below code snippet really mean in PostgreSQL while installing software?
./configure
make
make install
We will understand it in this post.
PostgreSQL is written in C, so installing PostgreSQL software is nothing but compiling and running all the C-Programs in your source code.
We will do that with an example.,
Table of Contents
How to compile and run a C program in Linux?
- Create a program called first.c
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[root@ison2 cmi]# cat first.c #include<stdio.h> int main(void) { printf("Hello! This is a test prgoram.\n"); } |
2. To compile this program, enter:
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[root@ison2 cmi]# gcc first.c -o first.o [root@ison2 cmi]# |
The above command will compile first.c program and creates an executable file called first.o.
3. To run the first.o just do ./first.o
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[root@ison2 cmi]# ls -lrt total 16 -rwxr-xr-x 1 root root 35 Mar 26 22:51 configure -rw-r--r-- 1 root root 83 Mar 26 22:54 first.c -rwxr-xr-x 1 root root 6449 Mar 26 22:58 first.o [root@ison2 cmi]# [root@ison2 cmi]# ./first.o Hello! This is a test prgoram. |
We can also execute the same program using make and makefile and make install.
How to use Make and Make install to run a C Program
Make is a general-purpose workflow program, usually used for compilation. But it can be used for anything.
When you do something like “make”, the make program executes a rule named “all“, by default from a file in the current directory named “Makefile”. This rule usually calls the compiler to compile some source code into binaries.
Makefile syntax
all:
{your compile code goes here}
install:
{your install code goes here}
make will open Makefile file and executes all part in it., i.e., it does exactly what “gcc first.c -o first.o” does above.
When you do “make install”, the make program takes the binaries from the previous step and copies them into some appropriate locations so that they can be accessed.
make install will open Makefile file and executes install part in it i.e., it does exactly what “./first.o” does above.
Let’s see how to use makefile with an example
- Create a Makefile with “all” and “install” fields.
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[root@ison2 cmi]# cat Makefile all: gcc first.c -o first.o install: ./first.o |
I just created a Makefile in vi editor with all: and install: fields and added the commands that I used earlier.
Now, do make and make install.
2. when you run make, it will look into Makefile file and run “all” section of the file.
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[root@ison2 cmi]# make gcc first.c -o first.o [root@ison2 cmi]# |
3. In the above step make created first.o and to run that, do make install.
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[root@ison2 cmi]# make install ./first.o Hello! This is a test prgoram. |
Want to add a display message to your Makefile?
You can do that with @echo.
Let me modify the Makefile
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[root@ison2 cmi]# cat Makefile all: gcc first.c -o first.o @echo All PostgreSQL has successfully made install: ./first.o |
Now run make.
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[root@ison2 cmi]# make gcc first.c -o first.o All PostgreSQL has successfully made [root@ison2 cmi]# |
Now that we understood how to run a program in Linux. We can do that with “./ProgramName”
Make and Makefile is really helpful if you have a bunch of C programs and quite a few rules to make.
write and run a simple shell script called configure.
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[root@ison2 cmi]# cat configure echo "I am checking configuration" [root@ison2 cmi]# ./configure I am checking configuration [root@ison2 cmi]# |
So what does the below snipped do in PostgreSQL?
Bringing up all the above three things together,
./configure
make
make install
configure: All the dependency check is written in configure, so look at the configure file with vi editor and try to read it if possible.
make: You will be having a makefile in the software directory which redirects you to src directory where you have all the programs, your make will compile all of them in the location specified in the location chosen in configure option.
make install: will run them.
And, that is the reason why you need GNU Make 3.80 or above and GCC installed on your Linux machine to install PostgreSQL.
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Words from postgreshelp
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