run_on_save.sh

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#!/bin/bash
##! Author:           Pieter van der Star (info@pietervanderstar.nl)
##! Modifications by: (unmodified)
##! 
##! This program is free software: you can redistribute it and/or modify
##! it under the terms of the GNU Affero General Public License as
##! published by the Free Software Foundation, either version 3 of the
##! License, or (at your option) any later version.
##! 
##! This program is distributed in the hope that it will be useful,
##! but WITHOUT ANY WARRANTY; without even the implied warranty of
##! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
##! GNU Affero General Public License for more details.
##! 
##! You should have received a copy of the GNU Affero General Public License
##! along with this program.  If not, see <https://www.gnu.org/licenses/>.
#
#
#Changelog:
#┏━━━━━━━━━━━━━━━┯━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┯━━━━━━━━━━━━━━━━━━━━━━━━━━┓
#┃   11 jun 2022 │ First release                            │   Pieter van der Star    ┃
#┠───────────────┼──────────────────────────────────────────┼──────────────────────────┨
#┃   24 feb 2024 │ Changed documentation comments to be     │   Pieter van der Star    ┃
#┃               │ compatible with my doxygen-bash-filter.  │                          ┃
#┠───────────────┼──────────────────────────────────────────┼──────────────────────────┨
#┃    9 may 2024 │ Readded spaces between the arguments.    │   Pieter van der Star    ┃
#┗━━━━━━━━━━━━━━━┷━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┷━━━━━━━━━━━━━━━━━━━━━━━━━━┛
 
##! @file
##! @brief This script can be used to automatically run a command as soon as a file is updated/saved.
echo "When waiting press: q to quit";
echo "                    r to rerun";
echo "                    f to show the file to wait on";
echo "                    c to show the command to run";
 
if [ $# -le 0 ]; then
    echo "Please enter a file to wait on as first argument.";
    exit;
fi
if [ $# -le 1 ]; then
    echo "Please enter bash script  to execute as second argument.";
    exit;
fi
#get the arguments, first the file
##! Name of the file to use as trigger.
file="$1";
shift;
#then the command
##! The command to execute on file modifications.
command="$1";
shift;
#string together all other arguments to make and run, these are the arguments
#to the program given in command
##! Arguments to pass to the command.
arguments="";
for arg in "$@"; do
    arguments+="$arg ";
done
 
echo "arguments: $arguments";
##! Last modified date when we previously ran the command.
prevlastmod=0;
 
while [ 1 -eq 1 ]; do #using [ 1 -eq 1 ] instead of true for wider compatibility
    lastmod=$(date -r "$file" +%s);
    if [ $? -ne 0 ]; then
        echo "file not found";
    else
        if [ "$lastmod" -gt "$prevlastmod" ]; then
            eval "$command $arguments";
            prevlastmod=$lastmod;
            echo "---------------------------RUN_ON_SAVE---------------------------";
        fi
    fi
    read -t 1 -n 1 key;
    if [ "$key" == 'q' ]; then
        echo "";
        exit;
    fi  
    if [ "$key" == 'r' ]; then
        prevlastmod=0;
        echo "";
    fi
    if [ "$key" == 'f' ]; then
        echo;
        echo "waiting on update of $file";
    fi
    if [ "$key" == 'c' ]; then
        echo;
        echo "after update run: \"$command $arguments\"";
    fi
done