Conditionally perform a command.

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

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.

For simple comparisons, a more concise option is to use a conditional operator instead of IF.
for example
[ "$var" = "snark" ] && echo "found snark"

instead of

if [ "$var" = "snark" ];
  then echo "found snark"

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

if is a bash builtin command.

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


case - Conditionally perform a command
eval - Evaluate several commands/arguments
expr - Evaluate expressions
for - Expand words, and execute commands
test - Evaluate a conditional expression
until - Execute commands (until error)
while - Execute commands
File operators -f
Equivalent Windows command: IF - Conditionally perform a command

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