To delete all blank white space (including spaces, tabs, and newlines) from input using sed, you can use the following command:
sed '/^\s*$/d'
This command will search the input for lines that consist only of zero or more white space characters (denoted by the \s* pattern), and delete them. The ^ and $ characters specify that the search should be performed at the beginning and end of the line, respectively. The d command tells sed to delete the matching lines.
For example, if you have the following input:
This is a test. This is another test.
Running the sed command above will output:
This is a test. This is another test.
You can also use the tr command to delete all white space characters from a file:
tr -d '[:space:]' < input_file > output_file
This will delete all white space characters (including spaces, tabs, and newlines) from the input_file, and write the resulting output to output_file.
By using the /^\s*$/d command in sed or the tr command, you can delete all blank white space from input. This can be useful for processing text data or for removing unnecessary characters from a script.