摘自http://www.computerhope.com/unix/ucut.htm
You can specify any character as the delimiter, however. For instance, the file /etc/passwd contains information about each user on the system, one user per line, and each information field is delimited by a colon (":"). For example, the line of /etc/passwd for the root user may look like this:
root:x:0:0:root:/root:/bin/bash
These fields contain the following information, in the following order, separated by a colon character:
Username
Password (shown as x if encrypted)
User ID number (UID)
Group ID number (GID)
Comment field (used by the finger command)
