 | Chapter 4 The Bourne Shell and Korn Shell |  |
! pipelineksh93 only. Negate the sense of a pipeline. Returns an exit status of 0 if the pipeline exited nonzero, and an exit status of 1 if the pipeline exited zero. Typically used in if and while statements.
This code prints a message if user jane is not logged on:
if ! who | grep jane > /dev/null then echo jane is not currently logged on fi
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| 4.9 Built-in Commands (Bourne and Korn Shells) |  | Reference: # |
