Bash memo for (if statement and test command)

Photo by Waldemar Brandt on Unsplash

Prerequisite knowledge

• The if statement determines the exit status of the command specified in the conditional expression and branches. True if the exit status is 0, false otherwise
• [ "A" = "A"] If there is no space between [] like this, an error will occur. For example ["A" = "A"], it is an error to write. It is easy to understand if [ is a command
• <,>,<=,>= cannot be used in conditional expressions. You can use -lt(<),-gt(>),-le(<=),-ge(>=) instead. -lt (less than), -gt (greater than), -le (less than or equal), -ge (greater than or equal), respectively. But it’s hard to understand, so I wrote it all down.
• If you have any trouble , just use man

Command collection

All you can find in this repo

GitHub - spy86/bash_if_statement_and_test_command

1. Are the strings equal?
2. Use > as a conditional expression → Use -gt (greater than)
3. Use < in a conditional expression → Use -lt (less than)
4. Use >= in a…