TRUE(1) General Commands Manual TRUE(1)

true — return true value

true

The true utility shall return with exit code zero.

None.

None.

Not used.

None.

None.

Default.

Not used.

Not used.

None.

None.

Zero.

None.

This utility is typically used in shell scripts, as shown in the EXAMPLES section.

Although the special built-in utility : ( colon(1)) is similar to true, there are some notable differences, including:

  • Whereas colon(1) is required to accept, and do nothing with, any number of arguments, true is only required to accept, and discard, a first argument of "--". Passing any other argument(s) to true may cause its behavior to differ from that described in this standard.
  • A non-interactive shell exits when a redirection error occurs with colon(1) (unless executed via command(1)), whereas with true it does not.
  • Variable assignments preceding the command name persist after executing colon(1) (unless executed via command(1)), but not after executing true.
  • In shell implementations where true is not provided as a built-in, using colon(1) avoids the overheads associated with executing an external utility.

This command is executed forever:

while true
do
    command
done

None.

None.

2.9 Shell Commands, colon, command(1), false(1)

First released in Issue 2.

IEEE Std 1003.1-2001 (“POSIX.1”)/Cor 1-2002, item XCU/TC1/D6/39 is applied, replacing the terms "None" and "Default" from the STDERR and EXIT STATUS sections, respectively, with terms as defined in 1.4 Utility Description Defaults.

Austin Group Defect 1640 is applied, clarifying the differences between true and : ( colon(1)).

June 14, 2024 posix.fail