Resolving IOS Configuration File Formatting Issues Natively in Windows

I find often myself working with Cisco configuration files that have been offloaded to an FTP or TFTP server. Fortunately Notepad++ is a wonderful tool that will handle these files properly and runs well on Windows. Unfortunately, I don’t always have a copy of Notepad++ at my fingertips. When trying to open an IOS created configuration file in the standard Windows Notepad, an irritating little issue arises. What happens is a formatting issue resulting from the fact that IOS terminates each line with a single “LF”, or “line feed”. This article takes a look at this common IOS Configuration File Formatting and demonstrates a way to resolve it without use of any third-party utilities.

To first demonstrate the problem, I have opened a file that was created in IOS and copied to my laptop using TFTP. The file, as rendered in Windows Notepad, looks like single continual line of text.

Notpad Wrap 1

Not having a real text editor at my disposal can be a bit of a drag. However, there is a quick way to rectify this without any third-party utilities. The way I typically work around this is using the Windows “find” command. This command seems to interpret the standalone “LF” as the end of a line when it parses the file. This single “LF” is how IOS terminates a line, but Windows Notepad expects a “CR/LF”, or “carriage return” followed by a “line feed”.

Given the fact that “find” can accurately determine the end of line is only part of the challenge. There is also a need to rewrite the file with “CR/LF” at the end of each line so Windows Notepad can properly interpret the file. Fortunately, the “find” command output can be used to create a new text file with the appropriate formatting. Here’s the full syntax I normally use.

find /v "some very random string of text" inputfile.cfg >> outputfile.cfg

By using this syntax, the /v parameter tells “find” to display all lines not containing “some very random string of text”.

Putting this in action with the previous example would look like the following.

find /v "adfasdfkjk" R1.cfg >> R1_out.cfg

Opening R1_out.cfg in notepad looks normal and is much more readable.

Output

Notepad Wrap 2

Conclusion

IOS devices seem to be able to handle either method of terminating a line. However, these devices produce configuration files that terminate a new line with a single “LF”. The demonstrated method of using the “find” command can be used to resolve IOS Configuration File Formatting issues for Windows users. By using this technique, a file is produced that can be properly rendered in  Windows Notepad.

About Paul Stewart, CCIE 26009 (Security)

Paul is a Network and Security Engineer, Trainer and Blogger who enjoys understanding how things really work. With over 15 years of experience in the technology industry, Paul has helped many organizations build, maintain and secure their networks and systems.
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4 Responses to Resolving IOS Configuration File Formatting Issues Natively in Windows

  1. Valeriy Simonov says:

    Or you can just open the file in Wordpad.

  2. Pingback: Exercising the Mind Versus Best Practice | PacketUPacketU

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