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#!/bin/bash

# The "tmuxifier"
# Execute parallel processes in an arbitrary number of tmux panes
# This script requires the path to an existing script to
# execute in parallel. Optionally, the number of threads to
# and the name of the tmux session can be input. If threads
# and session name are not entered, threads are determined
# automatically and session names is set to a default.

# Usage: 
#   tmuxp process [number of threads] [session name]
#   process      : name of the shell script or process to execute
#                  can be set to "" to only open tmux panes
#   threads      : number of threads to execute [optional]
#   session name : name of tmux session [optional]

# You will also need to edit the execution command ($exec_cmd)
# below which is what is run in each tmux pane. By default, it is:
#   "time $process $ct $nthread"
#   time     : the unix time command
#   $process : name of the process to execute
#   $ct      : the 0-indexed pane number, which I use as an 
#              argument in the $process script for parallelization
#   $nthread : the total number of threads, also used for as an
#              argument in $process for parallelization

# Michelle L. Gill, 2014-11-15

argc=$#

# Set the process name
if [[ $argc -ge 1 ]]; then
    process=$1
else
    echo "Usage: $0 process [number of threads] [session name]"
    exit 0
fi

# Set the number of threads, which corresponds to the number of panes
if [[ $argc -ge 2 ]]; then
    nthread=$2
else
    # Determine automatically on Mac or Linux
    if [[ `uname` == 'Darwin' ]]; then
        nthread=`sysctl hw.ncpu | awk '{print $2}'`
    else
        nthread=`nproc`
    fi
fi

# Set the session name 
if [[ $argc -ge 3 ]]; then
    sess_name=$3
else
    sess_name=tmuxifier
fi

# Test if the session exists
tmux has-session -t $sess_name 2> /dev/null
exit=$?
if [[ $exit -eq 0 ]]; then
    echo "Session $sess_name exists. Kill it? [y/N]"
    read kill_sess
    if [[ ($kill_sess == "y") || ($kill_sess == "Y") ]]; then
        tmux kill-session -t $sess_name
    else
        echo "Session not created because it already exists. Exiting."
        exit 0
    fi
fi

# Create the session
tmux new-session -d -s $sess_name

# Set the number of rows 
nrow=0
if [[ $nthread -eq 2 ]]; then
    nrow=2
elif [[ $nthread -gt 2 ]]; then
    # Ceiling function to round up if odd
    nrow=`echo "($nthread+1)/2" | bc`
fi

# Create the rows
ct=$nrow
while [[ $ct -gt 1 ]]; do
    frac=`echo "scale=2;1/$ct" | bc`
    percent=`echo "($frac * 100)/1" | bc`

    tmux select-pane -t $sess_name.0
    tmux split-window -v -p $percent
    (( ct-- ))
done

# Create the columns
if [[ $nthread -gt 2 ]]; then
    # Floor function to round down if odd
    ct=`echo "$nthread/2-1" | bc`
    while [[ $ct -ge 0 ]]; do
        tmux select-pane -t $sess_name.$ct
        tmux split-window -h -p 50
        (( ct-- ))
    done
fi

# Start the processes
if [[ $process != "" ]]; then
    ct=0
    while [[ $ct -lt $nthread ]]; do
        exec_cmd="time $process $ct $nthread"
        tmux send-keys -t $sess_name.$ct "$exec_cmd" Enter
        (( ct++ ))
    done
fi

tmux select-pane -t $sess_name.0

tmux -2 attach-session -t $sess_name