问题：SSH登录centos7系统后不停的刷日志，输入命令不生效
问题原因：配置了/etc/profile文件，文件中错误配置导致的。如我在文件末尾添加了source /etc/profile 引起了本次问题。
注意：系统级别环境变量谨慎修改
修复办法：进入单用户模式，修改profile文件。
错误日志：
-bash: /usr/bin/id: Argument list too long
-bash: [: : integer expression expected
-bash: /usr/bin/awk: Argument list too long
-bash: /usr/bin/sed: Argument list too long
-bash: /usr/bin/whoami: Argument list too long
-bash: /usr/bin/id: Argument list too long
-bash: /usr/bin/id: Argument list too long
-bash: /usr/bin/id: Argument list too long
-bash: /usr/libexec/grepconf.sh: Argument list too long
-bash: /usr/bin/tty: Argument list too long
-bash: /usr/bin/awk: Argument list too long
-bash: /usr/bin/who: Argument list too long
-bash: /usr/bin/id: Argument list too long
-bash: /usr/libexec/grepconf.sh: Argument list too long
-bash: /usr/bin/tty: Argument list too long
-bash: /usr/bin/who: Argument list too long
-bash: /usr/bin/awk: Argument list too long
-bash: /usr/bin/id: Argument list too long
-bash: [: : integer expression expected
-bash: /usr/bin/sed: Argument list too long
-bash: /usr/bin/awk: Argument list too long
-bash: /usr/bin/whoami: Argument list too long
-bash: /usr/bin/id: Argument list too long
-bash: /usr/bin/id: Argument list too long
-bash: /usr/bin/id: Argument list too long
-bash: /usr/libexec/grepconf.sh: Argument list too long
-bash: /usr/bin/tty: Argument list too long
-bash: /usr/bin/who: Argument list too long
-bash: /usr/bin/awk: Argument list too long
-bash: /usr/bin/id: Argument list too long
-bash: [: : integer expression expected
-bash: /usr/bin/awk: Argument list too long
-bash: /usr/bin/sed: Argument list too long
-bash: /usr/bin/whoami: Argument list too long
-bash: /usr/bin/id: Argument list too long
-bash: /usr/bin/id: Argument list too long
-bash: /usr/bin/id: Argument list too long
-bash: /usr/libexec/grepconf.sh: Argument list too long