There are several ways to remove blank lines from a text file using Linux command line utilities. Here are three options:
sed: You can use the sed command to delete blank lines from a file like this:sed '/^$/d' input.txt > output.txt
This will delete all blank lines from input.txt and write the output to output.txt.
grep: You can use the grep command to accomplish the same thing as follows:grep -v '^$' input.txt > output.txt
This will search input.txt for lines that do not begin with the empty string (^$) and write the output to output.txt.
awk: You can also use the awk command to remove blank lines from a file like this:awk 'NF > 0' input.txt > output.txt
This will search input.txt for lines that have at least one field (NF > 0) and write the output to output.txt.
Note that in all of these examples, the input file (input.txt) is not modified. Instead, the output is written to a new file (output.txt). If you want to modify the input file in place, you can use the -i option with sed or awk, or use the tee command with grep like this:
grep -v '^$' input.txt | tee input.txt
This will search input.txt for lines that do not begin with the empty string and write the output to both input.txt and the terminal.