{ claus.conrad }

Bash Scripting for Beginners - Complete Guide to Getting Started - If Statements (Part 5)

https://www.youtube.com/watch?v=YrE1Qg-Aw0Q

Video

Bash Scripting for Beginners: Complete Guide to Getting Started - If Statements (Part 5) - YouTube ^44a639

Notes

  • Basic syntax:
    mynum=200

if [ $mynum -eq 200 ]
then
    echo "The condition is true."
else
	echo "The condition is false."
fi
  • Checks within single brackets
    • Between variables/literals
      • Comparing integers
        • -eq (equal to)
        • -ne (not equal to)
        • -gt (greater than)
        • -ge (greater than or equal)
        • -lt (less than)
        • -le (less than or equal)
      • Comparing strings
        • = (equal to)
        • != (not equal to)
      • Comparing files
        • -nt (newer than)
        • -ot (older than)
    • Before the variable/literal
      • -f (regular file exists)
      • -d (directory exists)
      • -n (string has non-zero length)
      • -z (string has length zero)
    • Combining checks
      • && (and)
      • || (or)
  • Checks without brackets
    • command -v COMMAND (command exists)
    • COMMAND (command exits with return code 0)
  • ! reverses the following condition