Have you ever used | (Pipe) IOS command in a router?

This is a really cool way to filter text in output commands of Cisco routers. Please note that expressions you type with | commands are case sensitive (Typing serial0/1 instead of Serial0/1 will not work). In this tutorial a Cisco 3640 router has been used. Some | commands are not available in some routers depending on IOS version and model.

Type ‘show run | ?’ in order to see what are the available commands. Refer figure 1.

                                                                          Figure 1

Following ‘show run’ output has been used to explain commands ‘append, begin, redirect, section and tee’. Refer figure 2

                                                                              Figure 2

Append

This command can append an output of a show command into an existing file somewhere (ex: ftp, nvram). Give command ‘sh run | append ?’ to see what are the supported formats. Then issue ‘sh run | append '<'path to existing file'>'’. Refer figure 3

                                                                             Figure 3

Begin

This command can display an output starting from the given expression in it. As an example, if you want to display all lines after ‘Serial’ in show run output, command should be issued as ‘sh run | begin Serial’. Again remember that expressions are case sensitive. Refer figure 4

                                                                                   Figure 4

Tee

This command is similar to ‘append’ command but this creates a new file in given destination. Give command ‘sh run | tee ?’ to see what are the supported formats. Then issue ‘sh run | tee '<'path to new file'>'’. And also output is displayed on console at the same time. Refer figure 5

                                                                              Figure 5

Redirect

This command is similar to ‘tee’ command but output is not displayed on console at the same time. Give command ‘sh run | redirect ?’ to see what are the supported formats. Then issue ‘sh run | redirect '<'path to new file'>'’. Refer figure 6

                                                                             Figure 6

Section

This command can display a particular section of a show command. As an example, the section which is relevant to an interface in show run output can be viewed with ‘sh run | section '<'Interaface name'>'’. Refer figure 7

                                                                               Figure 7

The following ‘show ip route’ output has been used to explain commands ‘include and exclude’. Please note there are 2 ‘BGP’ routes and 3 ‘Connected’ routes in figure 8.

                                                                                Figure 8

Include

This command can display lines which include the given expression. As an example ‘sh ip ro | include B’ may filter out and display all BGP routes. Again remember that expressions are case sensitive. Instead of characters you can use numbers such as IP addresses too. Refer figure 9

                                                                             Figure 9

Exclude

This command can display lines which does not include (exclude) the given expression. As an example ‘sh ip ro | exclude B’ may filter out and display all routes except BGP routes. Again remember that expressions are case sensitive. Refer figure 10

                                                                               Figure 10

Hope you learned something new and valuable today. Make sure you practice them in order to learn where to apply correctly.

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