Linux file operation tips: delete multiple lines at the end

When using the Linux operating system for file processing, you often encounter situations where you need to delete multiple lines at the end of the file. This operation can usually be achieved through some simple commands. The following will introduce some common Linux file operation techniques and provide specific code examples.

1. Use the sed command to delete multiple lines at the end:

The sed command is a stream editor that can be used to process text. By combining the sed command and regular expressions, you can easily delete multiple lines at the end of the file.

The specific code is as follows:

sed -i '$d' file.txt

In this command,-imeans directly modifying the file content,$means matching the last line of the file,dmeans to delete the matching lines. After executing this command, the line at the end of filefile.txtwill be deleted.

If you need to delete multiple lines at the end, you can use the following command:

sed -i '{start_line_number},{end_line_number}d' file.txt

where{start_line_number}is the starting line number that needs to be deleted from the end.{end_line_number}is the end line number to be deleted. After executing this command, the contents from the starting line to the ending line in the filefile.txtwill be deleted.

2. Use the head command to delete multiple lines at the end:

The head command is usually used to display the header content of the file, but it can also be combined with-nParameter to choose to display the first few lines of the file.

The specific code is as follows:

head -n -$N file.txt > temp.txt && mv temp.txt file.txt

where$Nrepresents the number of rows that need to be deleted. In this command,head -n -$N file.txtwill output the contents of the file except the last N lines to thetemp.txttemporary file, and then pass ## The #mvcommand renames the temporary file to the original file namefile.txt, thereby achieving the effect of deleting multiple lines at the end.

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