while

Execute commands

Syntax
      while test-commands; do consequent-commands; done

      until test-commands; do consequent-commands; done

The while command continuously executes the do consequent-commands as long as the last command in list returns an exit status of zero.

The until command is identical to the while command, except that the test is negated; the do consequent-commands is executed as long as the last command in test-commands returns a non-zero exit status.

The exit status of the while and until commands is the exit status of the last do consequent-commands command executed, or zero if none was executed.

This is a BASH shell builtin, to display your local syntax from the bash prompt type: help while

"God shows his contempt for wealth by the kind of person he selects to receive it" ~ Austin O'Malley

Related macOS commands:

break - Exit from a loop
continue - Resume the next iteration of a while or if loop.
for - Loop command.
until - Execute commands (until error)