Sed command is very helpful for text processing. It’s just matter of regular expression. Here is how you can truncate empty lines in the file using command sed.
$ sed '/^\s*$/d' <file_name>
The above command will give you the output by deleting empty lines. If you want to modify the original file itself. You use the option -i
$ sed -i '/^\s*$/d' <file_name>
I have a file with following data and named as numbers
$ cat numbers 2989239823 8239823922 3892389239 2938923829 923892389 838888888 000000000
Now see, the way to truncate empty lines using sed
$ sed '/^\s*$/d' numbers 2989239823 8239823922 3892389239 2938923829 923892389 838888888 0000000000
The above command won’t change the original file. If you want to change original use option -i
sed -i '/^\s*$/d' numbers
Sed interprets ‘/^s*$/d’ and giving us the desired output. Here text between slashes(/regular expression/) represent the regular expression followed by sed command “d” means delete. So command sed matches the lines with given regular expression. If it finds the match it applies the command.