sg - 以 不 同 的 组 ID 执 行 命 令
sg [-] [group [-c ] command]
The sg command works similar to newgrp but accepts a command. The command will be executed with the /bin/sh shell. With most shells you may run sg from, you need to enclose multi-word commands in quotes. Another difference between newgrp and sg is that some shells treat newgrp specially, replacing themselves with a new instance of a shell that newgrp creates. This doesn't happen with sg, so upon exit from a sg command you are returned to your previous group ID.
The following configuration variables in /etc/login.defs change the behavior of this tool:
Enable "syslog" logging of sg activity.
/etc/passwd 用 户 账 户 信 息 。
/etc/shadow 安 全 用 户 账 户 信 息 。
/etc/group 组 账 户 信 息 。
/etc/gshadow 安 全 组 账 户 信 息 。