Clean up the Ubuntu system screenshots from ~/Pictures

screenshot_clean.sh

#! /usr/bin/env bash
#>------------------------------------------------------------------------------
#>
#> [ screenshot_clean.sh ]
#>
#> About:
#>
#>    Clean up the Ubuntu system screenshots from ~/Pictures
#>
#>    All screenshots are renamed and moved into a new directory located at
#>    ~/Pictures/Screenshots. The new file names are automatically derived and
#>    use the following schema:
#>
#>        <UNIX_TIME>-<YYmmddHHMMSS>.png
#>
#>    Consider auto-execution via cron (configurations for 'crontab -e'):
#>
#>        ## Daily at midnight:
#>        0 0 * * * /usr/local/bin/screenshot_clean.sh
#>
#>        ## Weekly on Monday at midnight:
#>        0 0 * * 1 /usr/local/bin/screenshot_clean.sh
#>
#>    Screenshots can be similarly archived from alternative directory locations
#>    in the manner described below in the "Usage" section.
#>
#> Usage:
#>
#>    screenshot_clean.sh <DIRECTORY>
#>    screenshot_clean.sh <OPTION>
#>
#>    where "DIRECTORY" is a valid directory reference; and where "OPTION" is
#>    one of the following:
#>
#>                |
#>    -h, --help  | Print this help text to the terminal
#>                |
#>
#>    NOTE: No inputs are required when executing this script. If no alternative
#>    directory is passed, this script will automatically execute on the files
#>    found in the ~/Pictures directory.
#>
#> Attribution:
#>
#>    Created on 20200715 by h8rt3rmin8r ([email protected])
#>
#> Source:
#>
#>    https://pastebin.com/YAUbYGFd
#>    https://gist.github.com/h8rt3rmin8r/fe5793bb8d35bbc9e3a3ff6de83e84fa
#>
#>------------------------------------------------------------------------------

# Declare functions

function sc_datemod() {
    # Date transformation function (date stamp into UNIX timestamp conversion)
    
    local i_all="$@"
    local out_len=10
    
    if [[ "${#i_all}" -lt 8 || "${i_all}" =~ [^0-9] ]]; then
        return 1
    fi
    
    local i_all_a=${i_all:0:8}
    local i_all_b=${i_all#$i_all_a}
    
    case "$(printf '%s' ${i_all_b} | wc -c)" in
        1|3|5)
            return 1
            ;;
        0)
            local i_time="00:00:00"
            ;;
        2)
            local i_time="${i_all_b}:00:00"
            ;;
        4)
            local i_time="${i_all_b:0:2}:${i_all_b: -2}:00"
            ;;
        6)
            local i_hour=${i_all_b:0:2}
            local i_minute_pre=${i_all_b#$i_hour}
            local i_minute=${i_minute_pre:0:2}
            local i_second=${i_all_b: -2}
            local i_time="${i_hour}:${i_minute}:${i_second}"
            ;;
        7|8|9|10|11|12|13|14|15|16|17|18|19|20)
            local i_hour=${i_all_b:0:2}
            local i_minute_pre=${i_all_b:0:4}
            local i_minute=${i_minute_pre: -2}
            local i_second_pre=${i_all_b:0:6}
            local i_second="${i_second_pre: -2}.${i_all_b:6}"
            local i_time="${i_hour}:${i_minute}:${i_second}"
        ;;
    esac
    
    local i_year=${i_all_a:0:4}
    local i_month_pre=${i_all_a:0:6}
    local i_month=${i_month_pre: -2}
    local i_day=${i_all_a: -2}
    local in_x="${i_year}-${i_month}-${i_day} ${i_time}"
    local output_prime=$(date -d "${in_x}" '+%s%N' 2>/dev/null)
    local e_c=$(date -d "${in_x}" '+%s%N' &>/dev/null; echo "$?")
    local output=${output_prime:0:$out_len}
    
    echo "${output}"
    
    return ${e_c}
}

function sc_help() {
    # Script help text printing function
    
    cat "${0}" \
        | grep -E '^#[>]' \
        | sed 's/^..//'
    
    return $?
}

function sc_l2a() {
    # File-lines-to-array conversion function
    
    if [[ -t 0 ]]; then
        if [[ "x${1}" == "x" ]]; then
            return 1
        fi
        
        if [[ -f "${1}" ]]; then
            mapfile -t L_ARR <"${1}"
        else
            return 1
        fi
    else
        return 1
    fi
    
    export L_ARR
    
    return $?
}

function sc_ls() {
    # Screenshot file listing function
    
    ls -CF "${t_d}" \
        | tr '\t' '\n' \
        | sed 's/\ \{2\}/\n/g' \
        | sed '/^[ ]*$/d' \
        | sed 's/^\ *//' \
        | sed 's/[*@]$//' \
        | sed '/[/]/d' \
        | LC_ALL=C sort \
        | grep -E '^S([cehnorst]){9}.from.([12][0-9][0-9][0-9])-(0[1-9]|1[0-2])-(0[1-9]|1[0-9]|2[0-9]|3[0-1]) (0[0-9]|1[0-9]|2[0-3])-([0-5][0-9])-([0-5][0-9])\.png'
    
    return $?
}

function sc_vb() {
    # Script verbosity printing function
    
    local runtime=$(date '+%s%N')
    local sh_name="${s_h}"
    local i_n="$@"
    
    echo "${runtime}|${sh_name}|${i_n}" &>/dev/stderr
    
    return $?
}

# Declare variables and arrays, then execute operations

_q1=$'\u0027'
_q2=$'\u0022'
_pa=$'\u0028'
_pb=$'\u0029'
_sp=$'\u0020'
_usd=$'\u0024'
s_h_pre="${0//*\/}"
s_h="${s_h_pre%[.]sh}"
r_t="$(date '+%s%N')"
n_c="${RANDOM:0:1}${RANDOM: -1}${RANDOM: -1}${RANDOM: -1}${RANDOM: -1}"
t_h="${HOME}"
t_d="${t_h}/Pictures"
o_d="${t_d}/Screenshots"
tmpf="/tmp/${s_h}_${r_t}-${n_c}"

declare -a sc_source=()
declare -a sc_outmod=()
declare -a sc_output=()

## Catch help text requests

if [[ "${1}" == "-h" || "${1}" =~ ^[-]+help$ ]]; then
    sc_help
    exit $?
fi

## Catch alternative target directory references

if [[ ! "x${1}" == "x" ]]; then
    if [[ -d "${1}" ]]; then
        t_d=$(readlink -f "${1}")
    else
        sc_vb "ERROR: Input is not a valid directory reference: ${1}"
        sc_vb "Use '--help' for more information"
        
        exit 1
    fi
fi

## Make the temp file
touch "${tmpf}"

## Store a list of valid screenshot images in the temp file
sc_ls >> "${tmpf}"

## Consume the lines of the temp file into an array, "L_ARR"
sc_l2a "${tmpf}"

## Kill the script if the "L_ARR" array has no elements
if [[ "${#L_ARR[@]}" -lt 1 ]]; then
    sc_vb "ERROR: No valid screenshots were found"
    rm "${tmpf}" &>/dev/null

    unset L_ARR
    unset sc_source
    unset sc_outmod
    unset sc_output
    unset sc_sequence

    exit 1
fi

## Loop through the discovered screenshot file names and generate three arrays
##
##    1) sc_source ==> same as "L_ARR"
##    2) sc_output ==> second half of the pending output file names
##    3) sc_outmod ==> date strings to be transformed in the following loop
##
for i in "${L_ARR[@]}"; do
    sc_vb "Processing: ${i}"
    
    ca_src="${i}"
    ca_out=$(sed 's/^.*from\ //' <<<"${ca_src}" | tr -d ' ' | tr -d '-')
    ca_mod=$(cut -d '.' -f1 <<<"${ca_out}")
    
    sc_source+=( "${ca_src}" )
    sc_output+=( "${ca_out}" )
    sc_outmod+=( "${ca_mod}" )
done

## Set variables and arrays required by the second loop processes
sc_count="${#sc_source[@]}"
let sc_count=sc_count-1
declare -a sc_sequence=( $(seq 0 1 ${sc_count}) )

## Clear out the temp file so it can be used as a parallel command file
echo -n > "${tmpf}"

for i in "${sc_sequence[@]}"; do
    ## Derive the parallel commands
    cb_src="${sc_source[$i]}"
    cb_mod_pre="${sc_outmod[$i]}"
    cb_mod=$(sc_datemod "${cb_mod_pre}")
    cb_out="${sc_output[$i]}"
    cb_a="${t_d}/${cb_src}"
    cb_b="${o_d}/${cb_mod}-${cb_out}"
    str_a="mv ${_q2}${cb_a}${_q2} ${_q2}${cb_b}${_q2};"
    str_b_a="echo ${_q2}${_usd}${_pa}date ${_q1}+%s%N${_q1}${_pb}"
    str_b_b="|${s_h}|Complete: ${cb_a} ==> ${cb_b}${_q2}"
    str_b="${str_b_a}${str_b_b}"
    
    ## Write the parallel commands into the temp file
    echo "${str_a} ${str_b}" >> "${tmpf}"
done

## Make sure the output directory exists
mkdir -p "${o_d}"

## Perform the file moving and renaming process using GNU Parallel
parallel --no-notice -k :::: "${tmpf}" 2>/dev/null

## Capture the exit code from the moving processes
e_c="$?"

##
## If the exit code was bad, inform the user that parallel should be installed
## if parallel cannot be found on the system; otherwise let the user know that
## something went wrong
##
if [[ "${e_c}" -ne 0 ]]; then
    sc_vb "ERROR: Missing required software 'parallel'"
    sc_vb "Install 'parallel' with: 'sudo apt-get install parallel' and try again"
fi

## Clean up the workspace (destroy the temp file and unset all arrays)
rm "${tmpf}" &>/dev/null

unset L_ARR
unset sc_source
unset sc_outmod
unset sc_output
unset sc_sequence

exit ${e_c}