if

Conditionally perform a command.

SYNTAX
      if test-commands; then
      consequent-commands;
      [elif more-test-commands; then
      more-consequents;]
      [else alternate-consequents;]
      fi

The test-commands list is executed, and if its return status is zero, the consequent-commands list is executed.

If test-commands returns a non-zero status, each elif list is executed in turn, and if its exit status is zero, the corresponding more-consequents is executed and the command completes.

If `else alternate-consequents' is present, and the final command in the final if or elif clause has a non-zero exit status, then alternate-consequents is executed.

The return status is the exit status of the last command executed, or zero if no condition tested true.

"Then you admit confirming not denying you ever said that?"
"NO! ... I mean Yes! WHAT?"
I'll put `maybe.' - Bloom County

Related commands:

case - Conditionally perform a command
eval - Evaluate several commands/arguments
expr - Evaluate expressions
for - Expand words, and execute commands
gawk - Find and Replace text within file(s)
m4 - Macro processor
until - Execute commands (until error)
while - Execute commands