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This article mainly introduces "how to remove blank lines with Cat commands under Linux". In daily operation, I believe many people have doubts about how to use Cat commands to remove blank lines under Linux. Xiaobian consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful to answer the doubts of "how to use Cat commands to remove blank lines under Linux". Next, please follow the editor to study!

Input files are printed in the order in which they are arranged after the Linux Cat command, so to change the order of the information, you must first change the order of the input files. In addition, when the number of files you need to process is too large for you to enter the names of those files manually, you can use wildcards, as used in catchapter* > book, keeping in mind that the file names will be sorted in ascending order. This raises interesting questions when you suddenly find that chapter13 is sent to the output before chapter2 and after chapter02.

When the output of the Linux Cat command is not redirected to the standard output of one file or another command, the Linux Cat command behaves like most command-line tools, sending its output to the console. This means that you can use the Linux Cat command to display the file; for example, you can use cat/etc/passwd to display the contents of the system password file. For convenience, you should use less to view large files, as in less/etc/passwd (you can learn more about less by typing manless).

Although the Linux Cat command is mainly used to merge files, you can also use it for simple automatic processing of input. For example, you can use a single blank line to remove multiple blank lines (using the-s option), which is a good way to clean up before you release the source code to the public. Unfortunately, cat does not have the option to clear all blank lines at once. But this is not a big deal, because you can use the convenient sed command to remove these blank lines:

Listing 1. Use the sed and Linux Cat commands to remove the blank line $cat-s/etc/X11/XF86Config | sed'/ ^ [[: space:]] * $/ d'

... # MultipleFontPathentriesareallowed (theyareconcatenatedtogether) # Bydefault,RedHat6.0andlaternowuseafontserverindependentof # theXservertorenderfonts. FontPath "/ usr/X11R6/lib/X11/fonts/TrueType" FontPath "unix/:7100" EndSection...

For source files that read configuration files and HTML pages, especially those generated by scripts that insert unnecessary new lines, and those that contain large conditional structures where items have been separated by blank lines, blank line compaction is a convenient technique.

Another important function of the Linux Cat command is that it can number lines. This function is convenient for the preparation of program documentation as well as legal and scientific documentation. The line number printed on the left makes it easy to reference a part of the document. This is very important in programming, scientific research, business reporting, or even legislative work. The line numbering feature has two options: the-b option (only non-blank lines can be numbered) and the-n option (all lines can be numbered):

At this point, the study on "how to use the Cat command to remove blank lines under Linux" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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