Linux shell 执行脚本的时候一般是会 fork 出一个子 shell，这样在有的时候就不方便了，比如要 unset 当前 shell 的环境变量等，
#!/usr/bin/env zsh if [ -z $http_proxy ]; then echo "not using proxy, set it now ... "; export http_proxy="http://127.0.0.1:1087"; export https_proxy="https://127.0.0.1:1087"; echo $http_proxy; else echo "using proxy now, unset it now ..."; unset http_proxy; unset https_proxy; echo $http_proxy; fi
. ./proxy_toggle.sh 或者
. (a period) is a bash shell built-in command that executes the commands from a file passed as argument, in the current shell.
source is a synonym for
From Bash man page:
. filename [arguments] source filename [arguments] Read and execute commands from filename in the current shell environment and return the exit status of the last command exe‐ cuted from filename. If filename does not contain a slash, file names in PATH are used to find the directory containing file‐ name. The file searched for in PATH need not be executable. When bash is not in posix mode, the current directory is searched if no file is found in PATH. If the sourcepath option to the shopt builtin command is turned off, the PATH is not searched. If any arguments are supplied, they become the posi‐ tional parameters when filename is executed. Otherwise the positional parameters are unchanged. The return status is the status of the last command exited within the script (0 if no commands are executed), and false if filename is not found or cannot be read.