1pssh(1) General Commands Manual pssh(1)
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6 pssh — parallel ssh program
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11 pssh [-vAiIP] [-h hosts_file] [-H [user@]host[:port]] [-l user] [-p
12 par] [-o outdir] [-e errdir] [-t timeout] [-O options] [-x args] [-X
13 arg] command ...
14 pssh -I [-vAiIP] [-h hosts_file] [-H [user@]host[:port]] [-l user] [-p
16 par] [-o outdir] [-e errdir] [-t timeout] [-O options] [-x args] [-X
17 arg] [command ...]
18
22 pssh is a program for executing ssh in parallel on a number of hosts.
23 It provides features such as sending input to all of the processes,
24 passing a password to ssh, saving output to files, and timing out.
25 The PSSH_NODENUM and PSSH_HOST environment variables are sent to the
27 remote host. The PSSH_NODENUM variable is assigned a unique number for
28 each ssh connection, starting with 0 and counting up. The PSSH_HOST
29 variable is assigned the name of the host as specified in the hosts
30 list. Note that sshd drops environment variables by default, so
31 sshd_config on the remote host must include the line:
32 AcceptEnv PSSH_NODENUM PSSH_HOST
33
36 -h host_file
37 --hosts host_file
38 Read hosts from the given host_file. Lines in the host file are
39 of the form [user@]host[:port] and can include blank lines and
40 comments (lines beginning with "#"). If multiple host files are
41 given (the -h option is used more than once), then pssh behaves
42 as though these files were concatenated together. If a host is
43 specified multiple times, then pssh will connect the given num‐
44 ber of times.
45 -H [user@]host[:port]
47 --host [user@]host[:port]
48 -H "[user@]host[:port] [ [user@]host[:port ] ... ]"
49 --host "[user@]host[:port] [ [user@]host[:port ] ... ]"
50 Add the given host strings to the list of hosts. This option
51 may be given multiple times, and may be used in conjunction with
52 the -h option.
53 -l user
55 --user user
56 Use the given username as the default for any host entries that
57 don't specifically specify a user.
58 -p parallelism
60 --par parallelism
61 Use the given number as the maximum number of concurrent connec‐
62 tions.
63 -t timeout
65 --timeout timeout
66 Make connections time out after the given number of seconds.
67 With a value of 0, pssh will not timeout any connections.
68 -o outdir
70 --outdir outdir
71 Save standard output to files in the given directory. Filenames
72 are of the form [user@]host[:port][.num] where the user and port
73 are only included for hosts that explicitly specify them. The
74 number is a counter that is incremented each time for hosts that
75 are specified more than once.
76 -e errdir
78 --errdir errdir
79 Save standard error to files in the given directory. Filenames
80 are of the same form as with the -o option.
81 -x args
83 --extra-args args
84 Passes extra SSH command-line arguments (see the ssh(1) man page
85 for more information about SSH arguments). This option may be
86 specified multiple times. The arguments are processed to split
87 on whitespace, protect text within quotes, and escape with back‐
88 slashes. To pass arguments without such processing, use the -X
89 option instead.
90 -X arg
92 --extra-arg arg
93 Passes a single SSH command-line argument (see the ssh(1) man
94 page for more information about SSH arguments). Unlike the -x
95 option, no processing is performed on the argument, including
96 word splitting. To pass multiple command-line arguments, use
97 the option once for each argument.
98 -O options
100 --options options
101 SSH options in the format used in the SSH configuration file
102 (see the ssh_config(5) man page for more information). This
103 option may be specified multiple times.
104 -A
106 --askpass
107 Prompt for a password and pass it to ssh. The password may be
108 used for either to unlock a key or for password authentication.
109 The password is transferred in a fairly secure manner (e.g., it
110 will not show up in argument lists). However, be aware that a
111 root user on your system could potentially intercept the pass‐
112 word.
113 -i
115 --inline
116 Display standard output and standard error as each host com‐
117 pletes.
118 --inline-stdout
120 Display standard output (but not standard error) as each host
121 completes.
122 -v
124 --verbose
125 Include error messages from ssh with the -i and \ options.
126 -I
128 --send-input
129 Read input and send to each ssh process. Since ssh allows a
130 command script to be sent on standard input, the -I option may
131 be used in lieu of the command argument.
132 -P
134 --print
135 Display output as it arrives. This option is of limited useful‐
136 ness because output from different hosts are interleaved.
137
140 Connect to host1 and host2, and print "hello, world" from each:
141 pssh -i -H "host1 host2" echo "hello, world"
142 Print "hello, world" from each host specified in the file hosts.txt:
144 pssh -i -h hosts.txt echo "hello, world"
145 Run a command as root with a prompt for the root password:
147 pssh -i -h hosts.txt -A -l root echo hi
148 Run a long command without timing out:
150 pssh -i -h hosts.txt -t 0 sleep 10000
151 If the file hosts.txt has a large number of entries, say 100, then the
153 parallelism option may also be set to 100 to ensure that the commands
154 are run concurrently:
155 pssh -i -h hosts.txt -p 100 -t 0 sleep 10000
156 Run a command without checking or saving host keys:
158 pssh -i -H host1 -H host2 -x "-O StrictHostKeyChecking=no -O
159 UserKnownHostsFile=/dev/null -O GlobalKnownHostsFile=/dev/null"
160 echo hi
161 Print the node number for each connection (this will print 0, 1, and
163 2):
164 pssh -i -H host1 -H host1 -H host2 'echo $PSSH_NODENUM'
165
167 If you have a set of hosts that you connect to frequently with specific
168 options, it may be helpful to create an alias such as:
169 alias pssh_servers="pssh -h /path/to/server_list.txt -l root -A"
170 Note that when an ssh command is terminated, it does not kill remote
172 processes (OpenSSH bug #396 has been open since 2002). One workaround
173 is to instruct ssh to allocate a pseudo-terminal, which makes it behave
174 more like a normal interactive ssh session. To do this, use pssh's
175 "-x" option to pass "-tt" to ssh. For example:
176 pssh -i -x "-tt" -h hosts.txt -t 10 sleep 1000
177 will ensure that all of the sleep commands will terminate (with SIGHUP)
178 after the 10 second timeout.
179 By default, ssh uses full buffering for non-interactive commands. Line
181 buffering may be preferrable to full buffering if you intend to look at
182 the files in an output directory as a command is running. To switch
183 ssh to use line buffering, use its "-tt" option (which allocates a
184 pseudo-terminal) using the "-x" option in pssh.
185 The ssh_config file can include an arbitrary number of Host sections.
187 Each host entry specifies ssh options which apply only to the given
188 host. Host definitions can even behave like aliases if the HostName
189 option is included. This ssh feature, in combination with pssh host
190 files, provides a tremendous amount of flexibility.
191
194 The exit status codes from pssh are as follows:
195 0 Success
197 1 Miscellaneous error
199 2 Syntax or usage error
201 3 At least one process was killed by a signal or timed out.
203 4 All processes completed, but at least one ssh process reported
205 an error (exit status 255).
206 5 There were no ssh errors, but at least one remote command had a
208 non-zero exit status.
209
212 Written by Brent N. Chun <bnc@theether.org> and Andrew McNabb <amcn‐
213 abb@mcnabbs.org>.
214 https://github.com/lilydjwg/pssh
216
219 ssh(1), ssh_config(5), pscp(1), prsync(1), pslurp(1), pnuke(1),
220 January 24, 2012 pssh(1)