When building AOSP 9.0.0_r30 source with these commands:
$ make clean
$ make showcommands -j8 > ~/BuildAndroid.txt
there are commands line like this in ~/BuildAndoird.txt:
[ 58% 62374/106553] PWD=/proc/self/cwd prebuilts/clang/host/linux-x86/clang-4691093/bin/clang++ ........
I suppose this is a bash command,but why there is "PWD=/proc/self/cwd" and a space(not ; or &&) before "prebuilts/clang/host/linux-x86/clang-4691093/bin/clang++"?What does this mean,I don't think it is legal for bash because space means the following text are parameters instead of command.
Another problem is,what is "/proc/self/cwd",is that a standard proc node?
Some experiment:
$ VAR=123
$ VAR=456 echo $VAR
123
$ echo $VAR
123
So this is really legal,but what is the meaning?
2 Answers
It executes the command
prebuilts/clang/host/linux-x86/clang-4691093/bin/clang++
but when setting up the environment for this command, it sets the environment variable PWD to the value /proc/self/cwd. Note that this affects only the environment of the clang++ process, not the environment/variable space of the shell script.
Try again:
VAR=123
VAR=456 echo $VAR
123
Ok, but:
VAR=456 /bin/sh -c 'echo $VAR'
456
