NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | ATTRIBUTES | SEE ALSO | NOTES
A while command repeatedly executes the while conditions and, if the exit status of the last command in the conditions list is 0, executes the do actions; otherwise the loop terminates. If no commands in the do actions are executed, then the while command returns a 0 exit status; until may be used in place of while to negate the loop termination test.
While conditions is TRUE (evaluates to nonzero), repeat commands between the while and the matching end statement. The while and end must appear alone on their input lines. If the shell's input is a terminal, it prompts for commands with a question-mark until the end command is entered and then performs the commands in the loop.
A while command repeatedly executes the while conditions and, if the exit status of the last command in the conditions list is zero, executes the do actions; otherwise the loop terminates. If no commands in the do actions are executed, then the while command returns a 0 exit status; until may be used in place of while to negate the loop termination test.
The built-in command continue may be used to terminate the execution of the current iteration of a while or until loop, and the built-in command break may be used to terminate execution of a while or until command.
In these examples, the user is repeated prompted for a name of a file to be located, until the user chooses to finish the execution by entering an empty line.
filename=anything while [ $filename ] do echo "file?" read filename # read from terminal find . -name $filename -print done |
set filename = anything while ( "$filename" != "" ) echo "file?" set filename = $< # read from terminal find . -name $filename -print end |
See attributes(5) for descriptions of the following attributes:
ATTRIBUTE TYPE | ATTRIBUTE VALUE |
---|---|
Availability | SUNWcsu |
Both the Bourne shell, sh, and the Korn shell, ksh, can use the semicolon and the carriage return interchangeably in their syntax of the if, for, and while built-in commands.
NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | ATTRIBUTES | SEE ALSO | NOTES