突然在服务器里发现这条 Linux 命令

运行了一次，感觉是些基本信息，应该不得哦

[gee@localhost root]$ CHECK_TYPE=SHELL; echo "INFO=${CHECK_TYPE} PID=$$ PPID=$PPID TTY=$(tty) SHELL=$0 HOME=$HOME PWD=$PWD| SHELL_END"
INFO=SHELL PID=6409 PPID=6408 TTY=/dev/pts/0 SHELL=bash HOME=/home/gee PWD=/root| SHELL_END

[root@localhost ~]# CHECK_TYPE=SHELL; echo "INFO=${CHECK_TYPE} PID=$$ PPID=$PPID TTY=$(tty) SHELL=$0 HOME=$HOME PWD=$PWD| SHELL_END"
INFO=SHELL PID=5294 PPID=5278 TTY=/dev/pts/0 SHELL=-bash HOME=/root PWD=/root| SHELL_END