Command: if

  Conditional execution of a command.

Syntax:

  1. IF [ NOT ] EXIST file "command"
  2. IF [ NOT ] ERRORLEVEL number "command"
  3. IF [ NOT ] string '==' word "command"
  4. IF [ NOT ] quoted-string '==' quoted-string "command"
  5. IF /I string==STRING

Options:

  command              Specifies the command to carry out if the condition
                       is met.
  NOT                  Specifies that the command shell should carry out
                       the command only if the condition is false.
                       (Without this, the command will be run if the
                       condition is true.)
  ERRORLEVEL number:   DOS Programs return a number when they exit,
                       which sometimes contains information on
                       whether the program was successful. If the
                       last program to exit returned the given number,
                       then the condition is true.
  string1==string2     If the two strings of characters are equal,
                       then the condition is true.
  exist [drive][path]  If the given file is there, then the condition
        filename       is true.
  /I string==STRING    Ignores uppercase / lowercase

Comments:

  Conditionally executes the specified "command". If the keyword NOT is
  specified, the condition is negated, meaning, the "command" is
  executed, if the condition evaluates to false.
  The first condition evaluates to true, if the specified file exists.
  Wildcards are supported. On local file systems one can test for
  character devices, too.
  The second variant evaluates to true, if the ERRORLEVEL is currently
  assigned to a number greater or equal than the specified number.
  ERRORLEVELS are assigned when external commands terminates or via
  CANCEL or QUIT.
  Due to compatibly with other DOS shells FreeCOM does not check, if the
  specified ERRORLEVEL is a number, but silently accepts any string. This
  allows to use the so-called Benny levels, where you can specify HA,
  HB, ... , HZ or xa, xb, ... , xz instead of 1, 2, ... , 26. Some
  malformed batch script use this syntax to make mapping of errorlevels
  to drive letters more visible. See example 5.
  The third and four ones are true, when the left string is case-
  sensitively equal to the string on the right side of the double equal
  sign. Either side may be quoted by double quotes, though, if the right
  side is not quoted, the first word is tested only.
  IF is a command internal to command.com and needs no other file
  in order to work.

Examples:

  Example 1:
    IF NOT EXIST c:\command.com ECHO There is no COMMAND.COM in C:\
  Executes the ECHO command, if a file C:\COMMAND.COM does not exist.
  Example 2:
    IF EXIST c:\FREEDOS\nul GOTO have_fdos_directory
  Branch the interpretation of the batch script to the label,
  if the file C:\FREEDOS\NUL exists. Because the filename NUL corresponds
  to the character device NUL:, which always exists, this test may be
  used to probe for the existance of the path C:\FREEDOS, because all
  character devices are virtually present in every directory of local
  filesystems.
  Example 3:
    IF %1==name ECHO First argument is "name"
  ECHO is executed, if the first argument of the current batch script is
  "name" (without the quotes). %1 may expand to any string, even with
  embedded whitespaces, but without an embedded double equal sign. Also,
  metacharacters included within the argument are evaluated.
  Example 4:
    IF "%1"=="first name" ECHO First argument is "first name"
  ECHO is executed, if the first argument of the current batch script is
  "first name" (without the quotes). %1 may expand to any string, even
  with embedded whitespaces or an embedded double equal sign or
  metacharacters.
  Example 5 (see options):
    "program"   (errorlevel refers to "program")
    SET drv=
    FOR %%Z IN (A B C D E F G H I J K L M N O P Q R S T U V W X Y Z) DO
    IF ERRORLEVEL H%%Z SET drv=%%Z
    (comment: the two lines are ONE line)
    IF ERRORLEVEL 27 SET drv=
    IF "%drv%"=="" goto error_no_drive_letter
  Assuming that "program" is setting the exit code to 1..26 for the drive
  letter, e.g. when searching for RAMdisks, this code snippet assigns the
  drive letter to the ENVIRONMENT VARIABLE drv or unsets the variable on
  error.
  Note: The following code is equal to the above one and fully compatible
  to all shells:
    "program"
    SET drv=
    IF ERRORLEVEL 1 SET drv=A (errorlevel refers to "program")
    IF ERRORLEVEL 2 SET drv=B
    IF ERRORLEVEL 3 SET drv=C
    ...
    IF ERRORLEVEL 25 SET drv=Y
    IF ERRORLEVEL 26 SET drv=Z
    IF ERRORLEVEL 27 SET drv=
    IF "%drv%"=="" goto error_no_drive_letter
  There are two more examples at "ERRORLEVEL / EXITCODE.
  Example 6:
    IF "example"=="EXAMPLE" echo Hello World!  (Hello World is NOT shown!)

    If /I "example"=="EXAMPLE" echo Hello World!  (Hello World is shown!)

Command: if

Syntax:

Options:

Comments:

Examples:

See also: