pdsh - issue commands to groups of hosts in parallel
pdsh [options]... command
pdsh is a variant of the rsh(1) command. Unlike rsh(1),
which runs commands on a single remote host, pdsh can run multiple
remote commands in parallel. pdsh uses a "sliding window"
(or fanout) of threads to conserve resources on the initiating host
while allowing some connections to time out.
When pdsh receives SIGINT (ctrl-C), it lists the status of
current threads. A second SIGINT within one second terminates the program.
Pending threads may be canceled by issuing ctrl-Z within one second of
ctrl-C. Pending threads are those that have not yet been initiated, or are
still in the process of connecting to the remote host.
If a remote command is not specified on the command line,
pdsh runs interactively, prompting for commands and executing them
when terminated with a carriage return. In interactive mode, target nodes
that time out on the first command are not contacted for subsequent
commands, and commands prefixed with an exclamation point will be executed
on the local system.
The core functionality of pdsh may be supplemented by
dynamically loadable modules. The modules may provide a new connection
protocol (replacing the standard rcmd(3) protocol used by rsh(1)), filtering
options (e.g. removing hosts that are "down" from the target
list), and/or host selection options (e.g., -a selects all hosts from
a configuration file.). By default, pdsh must have at least one
"rcmd" module loaded. See the RCMD MODULES section for more
information.
The method by which pdsh runs commands on remote hosts may
be selected at runtime using the -R option (See OPTIONS
below). This functionality is ultimately implemented via dynamically
loadable modules, and so the list of available options may be different from
installation to installation. A list of currently available rcmd modules is
printed when using any of the -h, -V, or -L options.
The default rcmd module will also be displayed with the -h and
-V options.
A list of rcmd modules currently distributed with
pdsh follows.
- rsh
- Uses an internal, thread-safe implementation of BSD rcmd(3) to run
commands using the standard rsh(1) protocol.
- exec
- Executes an arbitrary command for each target host. The first of the
pdsh remote arguments is the local command to execute, followed by
any further arguments. Some simple parameters are substitued on the
command line, including %h for the target hostname, %u for
the remote username, and %n for the remote rank [0-n] (To get a
literal % use %%). For example, the following would
duplicate using the ssh module to run hostname(1) across the
hosts foo[0-10]:
pdsh -R exec -w foo[0-10] ssh -x -l %u %h hostname
and this command line would run grep(1) in parallel
across the files console.foo[0-10]:
pdsh -R exec -w foo[0-10] grep BUG console.%h
- ssh
- Uses a variant of popen(3) to run multiple copies of the ssh(1)
command.
- mrsh
- This module uses the mrsh(1) protocol to execute jobs on remote hosts. The
mrsh protocol uses a credential based authentication, forgoing the need to
allocate reserved ports. In other aspects, it acts just like rsh. Remote
nodes must be running mrshd(8) in order for the mrsh module to work.
- qsh
- Allows pdsh to execute MPI jobs over QsNet. Qshell propagates the
current working directory, pdsh environment, and Elan capabilities to the
remote process. The following environment variable are also appended to
the environment: RMS_RANK, RMS_NODEID, RMS_PROCID, RMS_NNODES, and
RMS_NPROCS. Since pdsh needs to run setuid root for qshell support,
qshell does not directly support propagation of LD_LIBRARY_PATH and
LD_PREOPEN. Instead the QSHELL_REMOTE_LD_LIBRARY_PATH and
QSHELL_REMOTE_LD_PREOPEN environment variables will may be used and will
be remapped to LD_LIBRARY_PATH and LD_PREOPEN by the qshell daemon if
set.
- mqsh
- Similar to qshell, but uses the mrsh protocol instead of the rsh
protocol.
- krb4
- The krb4 module allows users to execute remote commands after
authenticating with kerberos. Of course, the remote rshd daemons must be
kerberized.
- xcpu
- The xcpu module uses the xcpu service to execute remote commands.
The list of available options is determined at runtime by
supplementing the list of standard pdsh options with any options
provided by loaded rcmd and misc modules. In some cases,
options provided by modules may conflict with each other. In these cases,
the modules are incompatible and the first module loaded wins.
- -w
TARGETS,...
- Target and or filter the specified list of hosts. Do not use with any
other node selection options (e.g. -a, -g, if they are
available). No spaces are allowed in the comma-separated list. Arguments
in the TARGETS list may include normal host names, a range of hosts
in hostlist format (See HOSTLIST EXPRESSIONS), or a single `-'
character to read the list of hosts on stdin.
If a host or hostlist is preceded by a `-' character, this
causes those hosts to be explicitly excluded. If the argument is
preceded by a single `^' character, it is taken to be the path to file
containing a list of hosts, one per line. If the item begins with a `/'
character, it is taken as a regular expression on which to filter the
list of hosts (a regex argument may also be optionally trailed by
another '/', e.g. /node.*/). A regex or file name argument may also be
preceeded by a minus `-' to exclude instead of include thoses hosts.
A list of hosts may also be preceded by "user@" to
specify a remote username other than the default, or
"rcmd_type:" to specify an alternate rcmd connection type for
these hosts. When used together, the rcmd type must be specified first,
e.g. "ssh:user1@host0" would use ssh to connect to host0 as
user "user1."
- -x
host,host,...
- Exclude the specified hosts. May be specified in conjunction with other
target node list options such as -a and -g (when available).
Hostlists may also be specified to the -x option (see the
HOSTLIST EXPRESSIONS section below). Arguments to -x may
also be preceeded by the filename (`^') and regex ('/') characters as
described above, in which case the resulting hosts are excluded as if they
had been given to -w and preceeded with the minus `-' character.
- -S
- Return the largest of the remote command return values.
- -h
- Output usage menu and quit. A list of available rcmd modules will also be
printed at the end of the usage message.
- -s
- Only on AIX, separate remote command stderr and stdout into two
sockets.
- -q
- List option values and the target nodelist and exit without action.
- -b
- Disable ctrl-C status feature so that a single ctrl-C kills parallel job.
(Batch Mode)
- -l user
- This option may be used to run remote commands as another user, subject to
authorization. For BSD rcmd, this means the invoking user and system must
be listed in the user´s .rhosts file (even for root).
- -t seconds
- Set the connect timeout. Default is 10 seconds.
- -u seconds
- Set a limit on the amount of time a remote command is allowed to execute.
Default is no limit. See note in LIMITATIONS if using -u with
ssh.
- -f number
- Set the maximum number of simultaneous remote commands to number.
The default is 32.
- -R name
- Set rcmd module to name. This option may also be set via the
PDSH_RCMD_TYPE environment variable. A list of available rcmd modules may
be obtained via the -h, -V, or -L options. The
default will be listed with -h or -V.
- -M name,...
- When multiple misc modules provide the same options to pdsh,
the first module initialized "wins" and subsequent modules are
not loaded. The -M option allows a list of modules to be specified
that will be force-initialized before all others, in-effect ensuring that
they load without conflict (unless they conflict with eachother). This
option may also be set via the PDSH_MISC_MODULES environment
variable.
- -L
- List info on all loaded pdsh modules and quit.
- -N
- Disable hostname: prefix on lines of output.
- -d
- Include more complete thread status when SIGINT is received, and display
connect and command time statistics on stderr when done.
- -V
- Output pdsh version information, along with list of currently
loaded modules, and exit.
- -n tasks_per_node
- Set the number of tasks spawned per node. Default is 1.
- -m block | cyclic
- Set block versus cyclic allocation of processes to nodes. Default is
block.
- -r railmask
- Set the rail bitmask for a job on a multirail system. The default railmask
is 1, which corresponds to rail 0 only. Each bit set in the argument to
-r corresponds to a rail on the system, so a value of 2 would
correspond to rail 1 only, and 3 would indicate to use both rail 1 and
rail 0.
- -a
- Target all nodes from machines file.
In addition to the genders options presented below, the genders
attribute pdsh_rcmd_type may also be used in the genders database to specify
an alternate rcmd connect type than the pdsh default for hosts with this
attribute. For example, the following line in the genders file
host0 pdsh_rcmd_type=ssh
would cause pdsh to use ssh to connect to host0, even if
rsh were the default. This can be overridden on the commandline with the
"rcmd_type:host0" syntax.
- -A
- Target all nodes in genders database. The -A option will target
every host listed in genders -- if you want to omit some hosts by default,
see the -a option below.
- -a
- Target all nodes in genders database except those with the
"pdsh_all_skip" attribute. This is shorthand for running
"pdsh -A -X pdsh_all_skip ..."
- -g
attr[=val][,attr[=val],...]
- Target nodes that match any of the specified genders attributes (with
optional values). Conflicts with the -a option. If used in
combination with other node selection options like -w, the
-g option will select from the supplied node list, instead of from
the genders file as a whole. Otherwise, This option targets the alternate
hostnames in the genders database by default. The -i option
provided by the genders module may be used to translate these to the
canonical genders hostnames. If the installed version of genders supports
it, attributes supplied to -g may also take the form of genders
queries. Genders queries will query the genders database for
the union, intersection, difference, or complement of genders attributes
and values. The set operation union is represented by two pipe symbols
('||'), intersection by two ampersand symbols ('&&'), difference
by two minus symbols ('--'), and complement by a tilde ('~'). Parentheses
may be used to change the order of operations. See the nodeattr(1) manpage
for examples of genders queries.
- -X
attr[=val][,attr[=val],...]
- Exclude nodes that match any of the specified genders attributes
(optionally with values). This option may be used in combination with any
other of the node selection options (e.g. -w, -g, -a,
-X may also take the form of genders queries. Please see
documentation for the genders -g option for more information about
genders queries.
- -i
- Request translation between canonical and alternate hostnames.
- -F filename
- Read genders information from filename instead of the system
default genders file. If filename doesn't specify an absolute path
then it is taken to be relative to the directory specified by the
PDSH_GENDERS_DIR environment variable (/etc by default). An
alternate genders file may also be specified via the
PDSH_GENDERS_FILE environment variable.
- -v
- Eliminate target nodes that are considered "down" by
libnodeupdown.
The slurm module allows pdsh to target nodes
based on currently running SLURM jobs. The slurm module is typically
called after all other node selection options have been processed, and if no
nodes have been selected, the module will attempt to read a running jobid
from the SLURM_JOBID environment variable (which is set when running under a
SLURM allocation). If SLURM_JOBID references an invalid job, it will be
silently ignored.
- -j jobid[,jobid,...]
- Target list of nodes allocated to the SLURM job jobid. This option
may be used multiple times to target multiple SLURM jobs. The special
argument "all" can be used to target all nodes running SLURM
jobs, e.g. -j all.
- -P
partition[,partition,...]
- Target list of nodes containing in the SLURM partition partition.
This option may be used multiple times to target multiple SLURM partitions
and/or partitions may be given in a comma-delimited list.
The torque module allows pdsh to target nodes
based on currently running Torque/PBS jobs. Similar to the slurm module, the
torque module is typically called after all other node selection
options have been processed, and if no nodes have been selected, the module
will attempt to read a running jobid from the PBS_JOBID environment variable
(which is set when running under a Torque allocation).
- -j
jobid[,jobid,...]
- Target list of nodes allocated to the Torque job jobid. This option
may be used multiple times to target multiple Torque jobs.
The rms module allows pdsh to target nodes based on an RMS
resource. The rms module is typically called after all other node
selection options, and if no nodes have been selected, the module will
examine the RMS_RESOURCEID environment variable and attempt to set the
target list of hosts to the nodes in the RMS resource. If an invalid
resource is denoted, the variable is silently ignored.
The SDR module supports targeting hosts via the System Data
Repository on IBM SPs.
- -a
- Target all nodes in the SDR. The list is generated from the "reliable
hostname" in the SDR by default.
- -i
- Translate hostnames between reliable and initial in the SDR, when
applicable. If the a target hostname matches either the initial or
reliable hostname in the SDR, the alternate name will be substitued. Thus
a list composed of initial hostnames will instead be replaced with a list
of reliable hostnames. For example, when used with -a above, all
initial hostnames in the SDR are targeted.
- -v
- Do not target nodes that are marked as not responding in the SDR on the
targeted interface. (If a hostname does not appear in the SDR, then that
name will remain in the target hostlist.)
- -G
- In combination with -a, include all partitions.
The nodeattr module supports access to the genders database
via the nodeattr(1) command. See the genders section above for a list
of support options with this module. The option usage with the
nodeattr module is the same as genders, above, with the
exception that the -i option may only be used with -a or
-g. NOTE: This module will only work with very old releases of
genders where the nodeattr(1) command supports the -r option,
and before the libgenders API was available. Users running newer versions of
genders will need to use the genders module instead.
The dshgroup module allows pdsh to use dsh (or Dancer's shell)
style group files from /etc/dsh/group/ or ~/.dsh/group/. The default search
path may be overridden with the DSHGROUP_PATH environment variable, a
colon-separated list of directories to search. The default value for
DSHGROUP_PATH is /etc/dsh/group.
- -g groupname,...
- Target nodes in dsh group file "groupname" found in either
~/.dsh/group/groupname or /etc/dsh/group/groupname.
- -X groupname,...
- Exclude nodes in dsh group file "groupname."
As an enhancement in pdsh, dshgroup files may optionally
include other dshgroup files via a special #include STRING syntax.
The argument to #include may be either a file path, or a group name,
in which case the path used to search for the group file is the same as if
the group had been specified to -g.
The netgroup module allows pdsh to use standard netgroup entries
to build lists of target hosts. (/etc/netgroup or NIS)
- -g groupname,...
- Target nodes in netgroup "groupname."
- -X groupname,...
- Exclude nodes in netgroup "groupname."
- PDSH_RCMD_TYPE
- Equivalent to the -R option, the value of this environment variable
will be used to set the default rcmd module for pdsh to use (e.g. ssh,
rsh).
- PDSH_SSH_ARGS
- Override the standard arguments that pdsh passes to the ssh(1)
command ("-2 -a -x -l%u %h"). The use of the parameters
%u, %h, and %n (as documented in the rcmd/exec
section above) is optional. If these parameters are missing, pdsh
will append them to the ssh commandline because it is assumed they are
mandatory.
- PDSH_SSH_ARGS_APPEND
- Append additional options to the ssh(1) command invoked by pdsh.
For example, PDSH_SSH_ARGS_APPEND="-q" would run ssh in quiet
mode, or "-v" would increase the verbosity of ssh. (Note: these
arguments are actually prepended to the ssh commandline to ensure they
appear before any target hostname argument to ssh.)
- WCOLL
- If no other node selection option is used, the WCOLL environment variable
may be set to a filename from which a list of target hosts will be read.
The file should contain a list of hosts, one per line (though each line
may contain a hostlist expression. See HOSTLIST EXPRESSIONS section
below).
- DSHPATH
- If set, the path in DSHPATH will be used as the PATH for the remote
processes.
- FANOUT
- Set the pdsh fanout (See description of -f above).
As noted in sections above pdsh accepts lists of hosts the
general form: prefix[n-m,l-k,...], where n < m and l < k, etc., as an
alternative to explicit lists of hosts. This form should not be confused
with regular expression character classes (also denoted by ``[]''). For
example, foo[19] does not represent an expression matching foo1 or foo9, but
rather represents the degenerate hostlist: foo19.
The hostlist syntax is meant only as a convenience on clusters
with a "prefixNNN" naming convention and specification of ranges
should not be considered necessary -- this foo1,foo9 could be specified as
such, or by the hostlist foo[1,9].
Some examples of usage follow:
Run command on foo01,foo02,...,foo05
pdsh -w foo[01-05] command
Run command on foo7,foo9,foo10
pdsh -w foo[7,9-10] command
Run command on foo0,foo4,foo5
pdsh -w foo[0-5] -x foo[1-3] command
A suffix on the hostname is also supported:
Run command on foo0-eth0,foo1-eth0,foo2-eth0,foo3-eth0
pdsh -w foo[0-3]-eth0 command
As a reminder to the reader, some shells will interpret brackets
('[' and ']') for pattern matching. Depending on your shell, it may be
necessary to enclose ranged lists within quotes. For example, in tcsh, the
first example above should be executed as:
pdsh -w "foo[01-05]" command
Originally a rewrite of IBM dsh(1) by Jim Garlick
<garlick@llnl.gov> on LLNL's ASCI Blue-Pacific IBM SP system. It is
now used on Linux clusters at LLNL.
When using ssh for remote execution, expect the stderr of
ssh to be folded in with that of the remote command. When invoked by
pdsh, it is not possible for ssh to prompt for passwords if
RSA/DSA keys are configured properly, etc.. For ssh implementations
that suppport a connect timeout option, pdsh attempts to use that
option to enforce the timeout (e.g. -oConnectTimeout=T for OpenSSH),
otherwise connect timeouts are not supported when using ssh. Finally,
there is no reliable way for pdsh to ensure that remote commands are
actually terminated when using a command timeout. Thus if -u is used
with ssh commands may be left running on remote hosts even after
timeout has killed local ssh processes.
Output from multiple processes per node may be interspersed when
using qshell or mqshell rcmd modules.
The number of nodes that pdsh can simultaneously execute
remote jobs on is limited by the maximum number of threads that can be
created concurrently, as well as the availability of reserved ports in the
rsh and qshell rcmd modules. On systems that implement Posix threads, the
limit is typically defined by the constant PTHREADS_THREADS_MAX.