Marco -51cto-linux Training-5-Regular expressions

Exercise: 1 . Displays the line in the/etc/passwd file that ends with bash.

cat/etc/passwd |grep ' bash$ '

2 . Displays the two-digit or three-digit number in the/etc/passwd file.

cat/etc/passwd |grep ' [[:d igit:]]\{2,3}\ '

3 . Displays the line with ' LISTEN ' followed by 0, one or more whitespace characters in the ' netstat-tan ' command result.

       cat/etc/passwd |grep ' listen[[:space:]]\{0,\}$ '

      4,

       useradd bash

       useradd testbash

       useradd basher

       useradd nologin-s/bin/nologin

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Marco -51cto-linux Training-5-Regular expressions