bash functions including date formatting

btamayo-functions.bash

#!/usr/bin/env bash


BLACK=$(tput setaf 0)
RED=$(tput setaf 1)
GREEN=$(tput setaf 2)
YELLOW=$(tput setaf 3)
LIME_YELLOW=$(tput setaf 190)
POWDER_BLUE=$(tput setaf 153)
BLUE=$(tput setaf 4)
MAGENTA=$(tput setaf 5)
CYAN=$(tput setaf 6)
WHITE=$(tput setaf 7)
BRIGHT=$(tput bold)
NORMAL=$(tput sgr0)
BLINK=$(tput blink)
REVERSE=$(tput smso)
UNDERLINE=$(tput smul)
RESET=$NORMAL


print_sub_step() {
    local spacer=" "
    local spacer_per_level=2
    
    ((limit = $1 * spacer_per_level))

    # In order to use brace expansion with a variable, we must use `eval`.
    # printf evaluates arguments as they come in. Here, there are $limit arguments
    # because of bash's brace '...' expansion. What ends up happening is this sequence
    # of calls in the background:
    #  printf %.s $spacer 1, then printf %.s $spacer 2, printf %.s $spacer 3, ... to $limit times
    # the format string '.s' is passed the number 1, 2, 3, etc. as a param, but is 
    # not expanded because of the dot ., which makes the field size zero.
    local prepad=$(eval "printf '%.s$spacer' {1..$limit} ")
    
    local input_string="[$2]"
    local string2=""

    local pad=$(printf '%0.1s' " "{1..80})

    # <prefix><prepad><input_string><pad><string2>
    
    printf '%s%s' "${CYAN}" "$prefix"
    printf '%s' "$prepad"
    printf '%s ' "$input_string"
    printf '%*.*s%s\n' 0 $((padlength - ${#prefix} - ${#prepad} - ${#input_string} - ${#string2} - ${#CYAN} - ${#RESET} )) "$pad" "$RESET"
}

print_substep_plain() {
    local spacer=" "
    local spacer_per_level=2
    
    ((limit = $1 * spacer_per_level))

    # In order to use brace expansion with a variable, we must use `eval`.
    # printf evaluates arguments as they come in. Here, there are $limit arguments
    # because of bash's brace '...' expansion. What ends up happening is this sequence
    # of calls in the background:
    #  printf %.s $spacer 1, then printf %.s $spacer 2, printf %.s $spacer 3, ... to $limit times
    # the format string '.s' is passed the number 1, 2, 3, etc. as a param, but is 
    # not expanded because of the dot ., which makes the field size zero.
    local prepad=$(eval "printf '%.s$spacer' {1..$limit} ")
    
    local input_string="$2"
    local string2=""


    # <prefix><prepad><input_string><pad><string2>
    
    printf '%s%s' "${prepad}${RESET}"
    printf '  %s\n' "$input_string" "$RESET"
}

print_step() {
    local pad=$(printf '%0.1s' " "{1..80})
    local string2=''
    local string1="[$1] "
    
    printf '%s' "$prefix"
    printf '%s' "$string1"
    printf '%*.*s' 0 $((padlength - ${#prefix} - ${#string1} - ${#string2} )) "$pad"
    printf '%s\n' "$string2"
}

dates() {
    cat << EOD
        Format/result           |       Command              |          Output
--------------------------------+----------------------------+------------------------------
YYYY-MM-DD_hh:mm:ss             | gdate +%F_%T                | $(gdate +%F_%T)
YYYYMMDD_hhmmss                 | gdate +%Y%m%d_%H%M%S        | $(gdate +%Y%m%d_%H%M%S)
YYYYMMDD_hhmmss (UTC version)   | gdate --utc +%Y%m%d_%H%M%SZ | $(gdate --utc +%Y%m%d_%H%M%SZ)
YYYYMMDD_hhmmss (with local TZ) | gdate +%Y%m%d_%H%M%S%Z      | $(gdate +%Y%m%d_%H%M%S%Z)
YYYYMMSShhmmss                  | gdate +%Y%m%d%H%M%S         | $(gdate +%Y%m%d%H%M%S)
YYYYMMSShhmmssnnnnnnnnn         | gdate +%Y%m%d%H%M%S%N       | $(gdate +%Y%m%d%H%M%S%N)
YYMMDD_hhmmss                   | gdate +%y%m%d_%H%M%S        | $(gdate +%y%m%d_%H%M%S)
Seconds since UNIX epoch:       | gdate +%s                   | $(gdate +%s)
Nanoseconds only:               | gdate +%N                   | $(gdate +%N)
Nanoseconds since UNIX epoch:   | gdate +%s%N                 | $(gdate +%s%N)
ISO8601 UTC timestamp           | gdate --utc +%FT%TZ         | $(gdate --utc +%FT%TZ)
ISO8601 UTC timestamp + ms      | gdate --utc +%FT%T.%3NZ     | $(gdate --utc +%FT%T.%3NZ)
ISO8601 Local TZ timestamp      | gdate +%FT%T%Z              | $(gdate +%FT%T%Z)
YYYY-MM-DD (Short day)          | gdate +%F\(%a\)             | $(gdate +%F\(%a\))
YYYY-MM-DD (Long day)           | gdate +%F\(%A\)             | $(gdate +%F\(%A\))
EOD
}