Parallel SSH

A simple shell script to broadcast SSH commands to multiple hosts in parallel.

Requires GNU Parallel.

Usage

Usage: pssh.sh [-nh] [-f HOSTLIST_FILE] [-l LOGFILE] [-s SSH_OPTIONS]
    [-p PARALLEL_OPTIONS] COMMAND ...

Runs COMMAND over SSH on all given hosts in parallel.

Requires GNU Parallel.

The string '{}' in COMMAND will be replaced with the hostname when
COMMAND is run.  Other template strings are available as well.  See the
GNU Parallel man page for more info.

-f HOSTLIST_FILE
    Specifies a file containing a list of hostnames to run commands on
    over SSH.  One hostname per line.  If this option is not provided,
    hostnames are read from stdin instead.

-l LOGFILE
    Specifies a file to write log output.  If not provided, logs are
    written to stdout.  Diagnostic information will always be written to
    stderr regardless of whether logs are written to stdout or a logfile.

-s SSH_OPTIONS
    Options to pass on to the SSH command.  If not provided, defaults
    to:
    -o StrictHostKeyChecking=no -o BatchMode=yes -x

-p PARALLEL_OPTIONS
    Options to pass on to the parallel command.  If not provided,
    defaults to:
    --no-notice --progress -P 0

-n
    Do not append a tag to the beginning of log output.  If this flag
    is not given, then every log line will be prefixed with the string
    "[hostname] " to make it easier to tell what lines in the output
    came from which host.

-h, --help
    Show this help output.

Example

Setup:

[damona ~]% cat > example_hosts
euclid.colorado.edu
verbs.colorado.edu
totally.bogus.hostname
[damona ~]% touch example_log

Run pssh:

[damona ~]% pssh.sh -f example_hosts -l example_log "echo hello from {}; hostname; boguscommand; echo bye from {}"

Computers / CPU cores / Max jobs to run
1:local / 8 / 3

Computer:jobs running/jobs completed/%of started jobs/Average seconds to complete
local:0/3/100%/0.0s 

Take a look at the output:

[damona ~]% cat example_log 
[totally.bogus.hostname] ssh: totally.bogus.hostname: Name or service not known
[euclid.colorado.edu] hello from euclid.colorado.edu
[euclid.colorado.edu] euclid.colorado.edu
[euclid.colorado.edu] zsh:1: command not found: boguscommand
[euclid.colorado.edu] bye from euclid.colorado.edu
[verbs.colorado.edu] hello from verbs.colorado.edu
[verbs.colorado.edu] verbs.colorado.edu
[verbs.colorado.edu] bye from verbs.colorado.edu
[verbs.colorado.edu] zsh:1: command not found: boguscommand