pdsh(1) General Commands Manual pdsh(1)
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 com‐
mands on a single remote host, pdsh can run multiple remote commands in
parallel. pdsh uses a "sliding window" (or fanout) of threads to con‐
serve 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 termi‐
nated with a carriage return. In interactive mode, target nodes that
time out on the first command are not contacted for subsequent com‐
mands, and commands prefixed with an exclamation point will be executed
on the local system.
The core functionality of pdsh may be supplemented by dynamically load‐
able 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 con‐
figuration file.). By default, pdsh must have at least one "rcmd" mod‐
ule 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 instal‐
lation. 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 fol‐
lowing 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
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)
mrsh This module uses the mrsh(1) protocol to execute jobs on remote
hosts. The mrsh protocol uses a credential based authentica‐
tion, 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.
krb4 The krb4 module allows users to execute remote commands after
authenticating with kerberos. Of course, the remote rshd dae‐
mons must be kerberized.
xcpu The xcpu module uses the xcpu service to execute remote com‐
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.
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 expres‐
sion 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 spec‐
ify 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
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
-q List option values and the target nodelist and exit without
-b Disable ctrl-C status feature so that a single ctrl-C kills par‐
allel job. (Batch Mode)
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
Set the connect timeout. Default is 10 seconds. This option may
also be set via the PDSH_CONNECT_TIMEOUT environment variable.
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. This option may also be set via the PDSH_COM‐
MAND_TIMEOUT environment variable.
Set the maximum number of simultaneous remote commands to num‐
ber. The default is 32.
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.
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.
-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
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
-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 ..."
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 ver‐
sion 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) man‐
page for examples of genders queries.
Exclude nodes that match any of the specified genders attributes
(optionally with values). This option may be used in combina‐
tion 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.
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 libnodeup‐
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
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 run‐
ning SLURM jobs, e.g. -j all.
Target list of nodes containing in the SLURM partition parti‐
tion. This option may be used multiple times to target multiple
SLURM partitions and/or partitions may be given in a comma-
The torque module allows pdsh to target nodes based on currently run‐
ning Torque/PBS jobs. Similar to the slurm module, the torque module is
typically called after all other node selection options have been pro‐
cessed, 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).
Target list of nodes allocated to the Torque job jobid. This
option may be used multiple times to target multiple Torque
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.
Target nodes in dsh group file "groupname" found in either
~/.dsh/group/groupname or /etc/dsh/group/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)
Target nodes in netgroup "groupname."
Exclude nodes in netgroup "groupname."
Equivalent to the -R option, the value of this environment vari‐
able will be used to set the default rcmd module for pdsh to use
(e.g. ssh, rsh).
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.
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).
If set, the path in DSHPATH will be used as the PATH for the
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 alterna‐
tive to explicit lists of hosts. This form should not be confused with
regular expression character classes (also denoted by ``''). For
example, foo 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 -- the list 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 nec‐
essary 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 <email@example.com> on
LLNL's ASCI Blue-Pacific IBM SP system. It is now used on Linux clus‐
ters 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 con‐
figured properly, etc.. For ssh implementations that suppport a con‐
nect timeout option, pdsh attempts to use that option to enforce the
timeout (e.g. -oConnectTimeout=T for OpenSSH), otherwise connect time‐
outs 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
The number of nodes that pdsh can simultaneously execute remote jobs on
is limited by the maximum number of threads that can be created concur‐
rently, as well as the availability of reserved ports in the rsh mod‐
ule. On systems that implement Posix threads, the limit is typically
defined by the constant PTHREADS_THREADS_MAX.
rsh(1), ssh(1), dshbak(1), pdcp(1)