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This specification describes a compact form for expressing a list of hostnames which contain an optional numerical part.
Name | github.com/flux-framework/rfc/spec_29.rst |
Editor | Mark A. Grondona <[email protected]> |
State | raw |
The hostlist is a somewhat well known format supported by
existing HPC tools such as pdsh,
powerman, and genders. The format is designed as a convenience
on systems where hostnames are assigned with a common prefix, a numeric
part, and an optional suffix. The result is a compact way to represent
a possibly large list of hosts by name, e.g. prefix[0-1024]
.
This RFC details the Flux implementation of the hostlist format.
A hostlist SHALL represent an ordered list of strings.
A hostlist string SHALL be a list of comma separated hostlist expressions.
A hostlist expression SHALL be a string of the form
prefix[idlist]suffix
, where all components prefix
, [idlist]
,
and suffix
are OPTIONAL.
An empty hostlist expression, ""
, SHALL represent an empty list.
The prefix and suffix components of a hostlist expression SHALL
consist of any printable, non-whitespace ASCII character besides the special
characters including square brackets: "[ ]
", and comma: ",
".
An idlist SHALL represent an ordered list of non-negative integer ids.
An idlist MAY be a simple comma-separated list, e.g. 5,4,10,11,12,13
.
Consecutive ids in an idlist MAY be compressed into hyphenated ranges,
e.g. 5,4,11-13
.
Leading zeros in the first element of an idlist SHALL be preserved
across all ids in the list, e.g. 005,4,11-13
represents the list
005,004,011,012,013
.
An idlist MAY contain repeated numbers, e.g. 2,2,2
is a valid list.
Within a hostlist expression, an idlist SHALL be enclosed in square
brackets, e.g. host[0-10,12]
.
""
=""
"foox,fooy,fooz"
="foox,fooy,fooz"
"[1-3,5-6]"
="1,2,3,5,6"
"foo[1-5]"
="foo1,foo2,foo3,foo4,foo5"
"foo[0-4]-eth2"
="foo0-eth2,foo1-eth2,foo2-eth2,foo3-eth2,foo4-eth2"
"foo1,foo1,foo1"
="foo1,foo1,foo1"
"[00-02]"
="00,01,02"
"[00-2]"
="00,01,02"
"foo[1,1,2,1]"
="foo1,foo1,foo2,foo1"