Here are the names for the POSIX minimum upper bounds for some of the above parameters. The significance of these values is that you can safely push to these limits without checking whether the particular system you are using can go that far. In most cases GNU systems do not have these strict limitations. The actual limit should be requested if necessary.
_POSIX_LINK_MAX ¶The most restrictive limit permitted by POSIX for the maximum value of a
file’s link count. The value of this constant is 8; thus, you
can always make up to eight names for a file without running into a
system limit.
_POSIX_MAX_CANON ¶The most restrictive limit permitted by POSIX for the maximum number of
bytes in a canonical input line from a terminal device. The value of
this constant is 255.
_POSIX_MAX_INPUT ¶The most restrictive limit permitted by POSIX for the maximum number of
bytes in a terminal device input queue (or typeahead buffer).
See Input Modes. The value of this constant is 255.
_POSIX_NAME_MAX ¶The most restrictive limit permitted by POSIX for the maximum number of
bytes in a file name component. The value of this constant is
14.
_POSIX_PATH_MAX ¶The most restrictive limit permitted by POSIX for the maximum number of
bytes in a file name. The value of this constant is 256.
_POSIX_PIPE_BUF ¶The most restrictive limit permitted by POSIX for the maximum number of
bytes that can be written atomically to a pipe. The value of this
constant is 512.
SYMLINK_MAX ¶Maximum number of bytes in a symbolic link.
POSIX_REC_INCR_XFER_SIZE ¶Recommended increment for file transfer sizes between the
POSIX_REC_MIN_XFER_SIZE and POSIX_REC_MAX_XFER_SIZE
values.
POSIX_REC_MAX_XFER_SIZE ¶Maximum recommended file transfer size.
POSIX_REC_MIN_XFER_SIZE ¶Minimum recommended file transfer size.
POSIX_REC_XFER_ALIGN ¶Recommended file transfer buffer alignment.