Use this command to make a FIFO special file. A FIFO special
file is a file that is typically used to send data from one process to
another so that the receiving process reads the data in first-in-first-out
(FIFO) format. A FIFO special file is also known as a named
pipe.
Requirements and Restrictions
- The parameters for this command are case-sensitive. You
must enter the parameters exactly as shown in the syntax
diagram.
- You can enter this command only in CRAS state or higher.
Format
- path
- is the path name of the new FIFO special file.
Additional Information
- Online help information is available for this command. To display
the help information, enter one of the following:
ZFILE HELP mkfifo
ZFILE HELP
ZFILE ?
In addition, the correct command syntax is displayed if you enter the syntax
incorrectly.
- The ZFILE mkfifo command is based on a subset of the mkfifo utility of the
Portable Operating System Interface for Computer Environments (POSIX)
standards.
- You can simplify the specification of the path name by using the ZFILE cd
command to change the working directory of your TPF terminal.
- This command does not read from the standard input (stdin)
stream.
This command does not write to the standard output (stdout)
stream.
You can redirect the standard error (stderr) stream from the
display terminal to a file by specifying one of the redirection characters
(2> or 2>>) followed by the file name to which you want
the error output written. The 2> character writes the error
output to a file. The 2>> character appends the error output
to an existing file.
- Note:
- When you use the > or 2> character, if the file that
you are redirecting data to already exists, the file is overwritten and any
data in that file is lost. If you do not want to overwrite the file,
ensure that you use the >> or 2>> character.
- This command supports the following three quoting mechanisms, which allow
you to override the special meaning of some characters:
- escape character (\)
- preserves the literal value of the character that follows. To
ignore the special meaning of a character, escape it by placing a backslash
(\) in front of it. In the example that follows, environment
variable PATH is /bin:/usr/bin:., the first
dollar sign ($) is escaped because of the preceding backslash, and the
second dollar sign takes on a special meaning.
User: ZFILE echo \$PATH is $PATH
System: $PATH is /bin:/usr/bin:.
- single quotation marks (' ')
- preserves the literal value of all characters between the opening single
quotation mark and the closing single quotation mark. For example,
entering ZFILE echo '*' displays an asterisk
character (*). Without the single quotation marks, the files
in the current working directory are displayed.
- double quotation marks (" ")
- preserves the literal value of all characters between the opening double
quotation mark and the closing double quotation mark except the dollar sign
($), the backquote (`), and the backslash (\).
This allows you to use the escape character inside double quotation marks,
which you cannot do in single quotation marks.
For example, entering ZFILE echo "\$PATH is \"$PATH\""
displays $PATH is "/bin:/usr/bin:."
If you want to use the literal meaning of any of the following
characters, you must always use a quoting mechanism:
left angle bracket (<)
| right angle bracket (>)
| ampersand (&)
|
backquote (`)
| backslash (\)
| dollar sign ($)
|
double quotation mark (")
| new-line (\n)
| left parenthesis ( ( )
|
right parenthesis ( ) )
| semicolon (;)
| single quotation mark (')
|
blank space
| tab
| vertical bar (|)
|
In addition, use a quoting mechanism when any of the following characters are
used in a way that takes on a special meaning but you want to use the literal
meaning:
asterisk (*)
| equal sign (=)
| left square bracket ( [ )
|
number sign (#)
| question mark (?)
| tilde (~)
|
Examples
In the following example, a FIFO special file named
my.new.fifo is created. In the display from
the ZFILE ls command, the size of the my.new.fifo
file cannot be determined; therefore, a value of -1 is displayed in
that field.
+---------------------------------------------------------------------------------------------+
|User: ZFILE mkfifo my.new.fifo |
| |
|System: FILE0003I 14:20:15 mkfifo my.n... COMPLETED SUCCESSFULLY. NO OUTPUT TO DISPLAY |
| |
|User: ZFILE ls -l -F |
| |
|System: FILE0001I 14:20:35 START OF DISPLAY FROM ls -l -F |
| total 3 |
| drwxrwxrwx 1 nobody nogroup 10 Sep 30 1999 conf/ |
| drwxrwxrwx 1 root bin 2 Sep 30 1999 htdocs/ |
| drwxrwxrwx 1 root bin 3 Nov 16 11:54 logs/ |
| prw-r--r-- 1 root bin -1 Mar 31 11:10 my.new.fifo| |
| END OF DISPLAY |
+---------------------------------------------------------------------------------------------+
Related Information
- See ZFILE ls-List File and Directory Names and Attributes for information about how to display information about
files.
- See Information Technology--Portable Operating System Interface
for Computer Environments (POSIX) for more information about the POSIX
standards.