I'm using centos in my VPS server and guest system. There're two logins for a guest system. One is root and one is regular. After I mounted the guest system and chroot to the mounting directory, I switched to the regular account in the mounted guest system. Then the brackets missed as shown below:
[root@server image]# chroot /mnt/guest34
[root@server /]# su - regular
-bash-4.1$ sd
-bash: sd: command not found