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Old SFTP clients regard
/ (slash) as a directory separator, which
requires the SFTP server to use some "tricks" to fool the clients. The SFTP client generally
does not have any inherent knowledge of MVS data sets and accesses all files as if they were
part of a hierarchical file system.
If an SFTP client tries to open the file
//FILE.NAME, the MVS data set
is actually opened. Some SFTP clients remove all consecutive slashes so that the file to be
/FILE.NAME. The SFTP server will interpret this as the HFS
FILE.NAME, located at the HFS root. To avoid this client behavior, the
SFTP server has other ways of naming MVS data sets. If a client tries to access the file
/FTADV:X=BIN/__FILE.NAME, the SFTP server interprets these as the data
//FILE.NAME. All these combinations are needed as it may be necessary
to make the SFTP clients pass the correct file or data set name to the server.
In z/OS, if a data set name is not enclosed in single quotes, the user prefix is added
in front of the data set name. For example, if user
USER1 has a data set
DATASET.NAME1, the user can access it using the data set name
//DATASET.NAME1. It is also possible to use an absolute prefixed name
Because single quotes are special characters in most environments, the SFTP server
introduces a new convention to use triple slashes to access absolute prefixed data set
names. The name becomes
///USER1.DATASET.NAME1. All combinations of slashes
and underscores can be used. For example,
USER1 can access his/her data set
using one of the following names:
//DATASET.NAME1 /_DATASET.NAME1 /FTADV:X=BIN/_/DATASET.NAME1 /FTADV:X=BIN/__DATASET.NAME1
//'USER1.DATASET.NAME1' /_'USER1.DATASET.NAME1' /FTADV:X=BIN/_/'USER1.DATASET.NAME1' /FTADV:X=BIN/__'USER1.DATASET.NAME1'
///USER1.DATASET.NAME1 //_USER1.DATASET.NAME1 /_/USER1.DATASET.NAME1 /__USER1.DATASET.NAME1 /FTADV:X=BIN/_/_USER1.DATASET.NAME1 /FTADV:X=BIN/_//USER1.DATASET.NAME1 /FTADV:X=BIN/__/USER1.DATASET.NAME1 /FTADV:X=BIN/___USER1.DATASET.NAME1
The choice of name type depends on the client. If consecutive slashes are not sent to
the server, "
/_" (or "
/__" for a prefixed absolute data
set) is probably the best choice. The SFTP client interprets the file path to be absolute
and does not add any directories in front of the name. If a file transfer advice string (see
File Transfer Advice String (FTADV)) is added in front of the file name,
__" (or "
___" for a prefixed absolute data set) is a
safe choice. The data set name becomes
client interprets it as an absolute path to the file and does not change it. The SFTP server
on the other hand recognizes the advice string
/FTADV:X=BIN/ and interprets
__DATASET.NAME1 to be the real name of the data set
z/OS has also library data sets, whose members are accessed using the data set name
Again, parentheses may be special characters in some environments. The SFTP server
introduces a new convention for accessing library members using a single slash as a member
separator. The name becomes
Because of the new conventions for data set names there are some exceptions in the HFS
file names. HFS file or directory name cannot start with an underscore if the file or
directory is located in the root directory. Also, if an advice string is used with
absolute HFS names, the HFS root must be written either as