Sed command file

SED as text manipulation tool that we use regularly and we think a lot of shell script is use regularly and SED stands for stream editor and basically allows you to manipulate text files substituting, replacing, searching, inserting, deleting without opening the files.

Moreover, SED enables us to use a regular expression to match the expression within the file and perform text manipulation. We have seen step by step definition and example using the SED command about replacing string and finding and replacing or redirecting the result to a new file or modifying the same file.

You may also have a look at the following articles to learn more —. The following output will appear after running the script. The following output will appear after running the above command.

Bash Programming Language. Python Programming Language. Perl Programming Language. Hypertext Markup Language. Extensible Markup Language. The following output will appear after running the above commands. It is necessary to escape the backslash in the file path for searching and replacing. Create a file named os. The following command will delete three lines from the file os.

So, this line and the next two lines will be deleted. Using [:blank:] class can be used to remove spaces and tabs from the text or the content of any file.

The following command will remove the spaces at the end of each line of the file, os. Create a text file named, input. PHP is a server-side scripting language. PHP is platform-independent. So, the following output will appear after running the above commands. Select any file that contains empty lines in the content to test this example.

Non-printable characters can be deleted from any text by replacing non-printable characters by none. Three lines exist in the file os. Create a file named web. So, the output contains just one line. This is why we have to run a cat command to see the original file.

All the first instances of the world apples have been changed to mango irrespective of the case. Being the second instance of the word in the same line it has not been replaced. As we saw above, the command we have been using so far only looks at the first occurrence in each line. To look at all instances of a word use -g along with the command.

Now suppose we just want to change the second occurrence of a word in each line. In the output, the only occurrence of colour in line 2 and the first occurrence in line 3 is left as it is.

The same is true for the third last line. By replacing g with any n, we can use sed to replace the nth occurrence of a word in each line.

Sometimes it is nice to space out each line in the file. We can mention specific lines to run the sed editor tool on. This would only make the changes in the lines mentioned explicitly and ignore the rest. We can see that only lines 2 to 4 have been modified.

The sed command can be used to remove certain lines while displaying. To save the output to another file we can use the redirection operator. The modifications made through sed command is only visible as an output on the command line. These outputs are not saved and the changes are not reflected in the original file. The file would be created in the current working directory. Just like performing multiple substitutions in the same command, sed can be used to display multiple consecutive lines in a single command.

The sed command can be used along with regular expressions to search for patterns. Regular expressions are used to specify certain rules that can be used to match the text and look for patterns. This solves the problem of matching Colour and colour as we have specified a regex for [Cc]olour which matches both the occurrences.