tee [−ai] [file...]
- Append the output to the files.
- Ignore the SIGINT signal.
- A pathname of an output file. If a file operand is '−', it shall refer to a file named −; implementations shall not treat it as meaning standard output. Processing of at least 13 file operands shall be supported.
- Provide a default value for the internationalization variables that are unset or null. (See the Base Definitions volume of POSIX.1‐2008, Section 8.2, Internationalization Variables for the precedence of internationalization variables used to determine the values of locale categories.)
- If set to a non-empty string value, override the values of all the other internationalization variables.
- Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as opposed to multi-byte characters in arguments).
- Determine the location of message catalogs for the processing of LC_MESSAGES.
- The standard input was successfully copied to all output files.
- An error occurred.
... | tee unsorted | sort > sorted
"tee: cannot access %s\n", <pathname>