Uly.me

cloud engineer

Leading Zeros For Numbers Below 10

When displaying in a time format, it’s best to display numbers below 10 with leading zeros.

Here’s a nice function you can call to covert numbers below 10.

convert ()
{
    # print the number as a string with a leading zero
    number=$(printf '%02d\n' "$1")
    echo $number
}
convert 5

Result

05

Check if Multiple Arguments

If your Bash script calls for 3 arguments, here’s how to check it.

if [ "$#" -ne 3 ]
then
  echo "Usage: ./script.sh project diskname policy"
  exit
fi

You can adjust -ne 3 to any number based on the number of required arguments.

Fallocate

If you want to create dummy files, there’s a faster command than ‘dd’ called ‘fallocate.’

Create a 30GB called temp_30GB_file.

fallocate -l 30G temp_30GB_file

Unlike dd which can take minutes depending on file size, fallocate is instantaneous.