On Sat, Jul 20, 2024 at 06:17:46 +0800, p...@gmx.it wrote: > $ VAR=foo ./a.sh > i can see VAR=foo
I don't know what "see" means here. hobbit:~$ cat a.sh #!/bin/sh echo "I am a.sh, and inside me, VAR=<$VAR>." hobbit:~$ unset -v VAR hobbit:~$ VAR=foo ./a.sh I am a.sh, and inside me, VAR=<foo>. hobbit:~$ echo "VAR=<$VAR>" VAR=<> VAR is defined in the environment of a.sh but NOT in the calling shell. > > What's the difference between these two commands? > > VAR3=foo ./a.sh > > VAR3=bar; ./a.sh > > > > In the first command, VAR3 is placed in the environment of the command > > being executed. ./a.sh will see it. VAR3 will not survive beyond > > this command. It will be discarded, and future commands will not be > > aware it ever existed. > > > > In the second command, VAR3 is created as a regular variable in the > > current shell, but not exported to the environment. It will NOT be > > seen by ./a.sh, but it WILL be seen by future shell commands within > > this session. > > I can not clearly understand for this statement. what's "future shell > commands"? can you show an example? hobbit:~$ unset -v VAR hobbit:~$ VAR=bar; ./a.sh I am a.sh, and inside me, VAR=<>. hobbit:~$ echo "VAR=<$VAR>" VAR=<bar>
