How to get a shell environment variable in a makefile

Question

In shell when I enter  echo  demoPath   it prints   usr local demo   How can I get the value of this variable  demoPath in a makefile

User · Answer

for those who want some official document to confirm the behavior

Variables in make can come from the environment in which make is run. Every environment variable that make sees when it starts up is transformed into a make variable with the same name and value. However, an explicit assignment in the makefile, or with a command argument, overrides the environment. (If the ‘-e’ flag is specified, then values from the environment override assignments in the makefile.

https://www.gnu.org/software/make/manual/html_node/Environment.html

User · Answer

all      echo   PATH    Or change PATH just for one command   all      PATH  my path   PATH  cmd

User · Answer

If you ve exported the environment variable   export demoPath  usr local demo   you can simply refer to it by name in the makefile  make imports all the environment variables you have set    DEMOPATH     demoPath       Or   demoPath  if you prefer    If you ve not exported the environment variable  it is not accessible until you do export it  or unless you pass it explicitly on the command line   make DEMOPATH    demoPath         If you are using a C shell derivative  substitute setenv demoPath  usr local demo for the export command

[shell] How to get a shell environment variable in a makefile?

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