The POSIX subsystem must be activated before it is possible to process files in the POSIX file system.
The POSIX file names in the statements which permit access to POSIX files are path names in the POSIX file system. EDT cannot be used to move to a position within the POSIX file system. If no absolute path name (starting with '/') is specified then the file names always refer to the current directory. When the call is issued from BS2000, this is the user's home directory.
POSIX file names used in EDT statements must comply with the requirements of the POSIX file system. In particular, the maximum permitted length is 1023 bytes. It can be specified directly as a string or indirectly as a string variable. If the name of a POSIX file contains blanks or other special characters then it must be specified by means of a string variable.
POSIX file names are case-sensitive. Consequently, when input is made from a terminal, @PAR LOWER=ON should be activated.
EDT reads data character-by-character. The end of a record is recognized by means of the (character set-specific) end-of-record character (for example X'15' in EBCDIC or X'0A' in ISO character sets). If a record is detected, it is placed in the current work file. If two endof-record characters occur one after the other then a record of length 0 is generated in the work file.
If when reading a POSIX file, no end-of-record is recognized after 32768 characters then EDT outputs the message EDT1253, truncates the output and ignores the characters through to the next end-of-record character.
When the content of the work file is written to the POSIX file, a (character set-specific) endof-record character (for example X'15' in EBCDIC or X'0A' in ISO character sets) is written after every work file record.
In the case of records of length 0, only an end-of-record character is written.
When writing write-protected POSIX files under the user ID TSOS in interactive mode, the message EDT0244 is issued to ask the user whether write access is to be permitted. If it is not, EDT issues the message EDT5312. In batch mode, EDT issues the message EDT5312 and does not permit write access.
Unlike in the case of BS2000 files or library elements, the system permits the multiple opening of the same POSIX file. EDT does not prevent this. Users must therefore take the necessary care and attention.