子shell 进程ID($$) 博客分类： linux运维 脚本 shell
程序员文章站
2024-03-14 23:36:29
...
shell脚本中$$指当前进程ＩＤ,而调用$()执行命令时会生成子shell,按理说$()中用$$获取到的进程号是子shell的进程ID,但shell的规则是它获取到的是current shell的pid,而current_shell的进程id在这表现为派生子shell的shell进程ＩＤ
#!/bin/bash
echo $$
test(){
echo $$
}
$(test)
第一个$$和test里的$$输出是一样的.他们的current_shell 都是父shell
看看info bash里的说明
`$'
Expands to the process ID of the shell. In a `()' subshell, it
expands to the process ID of the invoking shell, not the subshell.
再看看man bash里的说明
$
Expands to the process ID of the shell. In a () subshell, it expands to the process ID of the current shell, not the subshell.
#!/bin/bash
echo $$
test(){
echo $$
}
$(test)
第一个$$和test里的$$输出是一样的.他们的current_shell 都是父shell
看看info bash里的说明
`$'
Expands to the process ID of the shell. In a `()' subshell, it
expands to the process ID of the invoking shell, not the subshell.
再看看man bash里的说明
$
Expands to the process ID of the shell. In a () subshell, it expands to the process ID of the current shell, not the subshell.