I have a C++ program that will run on several machines that use a Network File System. For each of the C++ libraries that my program uses, I installed a version for each machine, under ~/program_files/machinename/libraryname.
"machinename" is obtained via bash command "hostname". On the machines I am using, "hostname" outputs something like "io21.aaa.bbb.edu" and I take only "io21" as "machinename" for the path to the libraries. In bash, I learned that
$ HOST=
hostname# now the value of HOST is "io21.aaa.bbb.edu"$ HOST=${HOST%%.*} # extract "io21" from "io21.aaa.bbb.edu"
$ echo ${HOST}
io21
In the Makefile of my program, I want to call these bash commands to specify the path to the library according to the current machine:
HOST := $(shell hostname)
HOST := $(shell ${HOST%%.*})
LDFLAGS=-L${HOME}/program_files/${HOST}/libraryname/lib
CXXFLAGS=-Wall -I${HOME}/program_files/${HOST}/libraryname/include
The first line is working i.e. HOST is "io21.aaa.bbb.edu", but the second line which extracts "io21" doesn't work and HOST is still "io21.aaa.bbb.edu".
I am wondering how I should solve this problem?
Thanks and regards!
Alternatively you can use
HOST := $(shell echo $(HOST) | cut -d . -f 1)