Technical data

Table 2–3: Absolute and Relative File Specification Differences
OpenVMS
UNIX
Therelativepathforfile
calc;1
in
directory
usr:[jones]
is:
[.accounting.calc;1]
Theabsolutepathis:
usr:[jones.accounting.calc;1]
The relative pathname for file
calc
in
directory
/usr/jones
is
accounting/calc
The absolute pathname is
/usr/jones/accounting/calc
On UNIX systems, absolute pathnames
use the entire directory path that leads to
the file, beginning with the root, which is
represented by an initial slash.
The root directory is the first directory
in the file system. All other files and
directories trace their ancestry back to
the root. Relative pathnames begin the
directory path with the current working
directory and exclude the current working
directory name in the pathname. There is
no initial slash in a relative pathname.
2.2.4 File Specifications
There are fundamental differences between file names specified in OpenVMS and
in UNIX. Table 2–4 describes those differences.
Table 2–4: File Specification Differences
OpenVMS (ODS-2)
UNIX
Includes, in this order:
1. the file name
2. the file type
3. an optiona
l version number
An OpenVMS file specification can have a
maximum of 255 characters.
Thefilena
meandfiletypecanhaveupto
39 charact
ers each and are separated by a
period. F
or example:
FILE_NAME.TXT;1
Valid characters in an OpenVMS file name
or type include: A–Z, a–z, 0–9, underscore
(_), hyphen (-), and dollar sign ($). The
version number (preceded by a semicolon)
is a decimal number from 1 to 32767; it
differentiates versions of the same file.
Contains up to 1024 characters, with each
element of the pathname containing up to
255 characters. UNIX file specifications
have the following format:
file_nam
e.txt
Some older versions of the UNIX operating
system limit the size of one element to 14
characters, or have other limits that you
can change if you recompile the kernel.
In theory, you can use any ASCII character
in a UNIX pathname except for the slash (/)
and null characters. For example, a valid
file name in UNIX can be:
report.
from.january_24
However, avoid characters (such as the
pipe (|) character) that can have special
meaning to the UNIX shell.
2.2.5 Case Sensitivity
Case sensitivity differs between the two operating systems. Table 2–5 describes
the difference.
2–6 Understanding OpenVMS and UNIX Implementations