Generate markdown table calendar. Use wiki links to individual days

md-cal.sh

# Author: Daniel Brandenburg
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU 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 General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.
#
#
# Original: https://gist.github.com/jdbrice/3b7395d7f1ff724a744a26ab9bfd078b


######################################################################
# OPTIONS
#relative or full path to output file
outputFile="calendar.md"
# Date range to generate
startDate=2020-07-01
endDate=2020-07-31

# use `date` on linus, for OSX set this to `gdate` you may need to install it (brew install coreutils)
date_cmd="gdate"

# controls the link format for each day:
# [[ $linkFormat | $displayFormat ]]
# Note: you can include `XX` immediately after the day number to get the ordinal suffix
linkFormat="%Y-%b-%dXX-%a"
displayFormat="%e"

# marker for empty days in calendar view
emptydays="--"

monthHeadingLvl="# " # the heading used for the months
monthHeadingFormat="%B, %Y"

# table headers
hWeek="Week"
hMon="Mon"
hTue="Tue"
hWed="Wed"
hThu="Thu"
hFri="Fri"
hSat="Sat"
hSun="Sun"

#####################################
# should we check for file existance?
# if false the following options wont work
# checking all the files is a little slow, 
# so you can turn it off if you want
checkFileExists=true

#no trailing slash please
dailyNotePath="<path_to_obsidian_vault_daily_notes>"

# Should non-existing notes get linked?
linkNonExisting=true

#highlight the link for (non)existing
# link is wrapped with this e.g. ** [[ link | display ]] **
hle="**" #exsting or used for all if checkFileExists=false
hlne="" # not existing
hlt="==" #highlight for today's date (in addition to others)


# END OPTIONS
######################################################################

# Count the number of daily notes that you have
# TODO:
# - breakdown by day / week / month
# - consider metrics on files themselves (word count etc.)
countExistingNotes=0
countNonExistingNotes=0

# initialize the output file
echo "" > "$outputFile"
curr="$startDate"

DaySuffix() {
  case `$date_cmd +%-d --date "$curr"` in
    1|21|31) echo "st";;
    2|22)    echo "nd";;
    3|23)    echo "rd";;
    *)       echo "th";;
  esac
}

function print_day_wiki_link {

    if [ "$checkFileExists" != true ]; then 
        printf "| $hle[[ %s \| %s ]]$hle " "`$date_cmd +$linkFormat --date "$curr"`" "`$date_cmd +$displayFormat --date "$curr"`" >> "$outputFile"
        return
    fi

    day_suffix=$(DaySuffix)
    # replace the string 'XX' with the day suffix if it is found within the linkFormat string
    linkTemplate=${linkFormat/XX/$day_suffix}

    # Main link output
    testFile="$dailyNotePath/`$date_cmd +$linkTemplate --date "$curr"`.md"

    hil="" #no highlight by default
    if [ `$date_cmd +%Y-%m-%d --date "$curr"` == `$date_cmd +%Y-%m-%d`  ]; then
        hil="$hlt"
    fi

    if [ -e "$testFile" ]; then # Daily note file exists
        printf "| $hil$hle[[ %s \| %s ]]$hle$hil " "`$date_cmd +$linkTemplate --date "$curr"`" "`$date_cmd +$displayFormat --date "$curr"`" >> "$outputFile"
        countExistingNotes=$((countExistingNotes+1))
    elif [ "$linkNonExisting" == true ]; then # Daily note file does not exists, but still make a link
        printf "| $hil$hlne[[ %s \| %s ]]$hlne$hil " "`$date_cmd +$linkTemplate --date "$curr"`" "`$date_cmd +$displayFormat --date "$curr"`" >> "$outputFile"
        countNonExistingNotes=$((countNonExistingNotes+1))
    elif [ "$linkNonExisting" == false ]; then # Daily note DNE and also do not link
        printf "| $hil$hlne%s$hlne$hil " "`$date_cmd +$displayFormat --date "$curr"`" >> "$outputFile"
        countNonExistingNotes=$((countNonExistingNotes+1))
    fi
}

while true; do
    # echo "$curr"
    [ "$curr" \< "$endDate"  ] || break

    # Print the table header on the first day of the month
    if [ `$date_cmd +%d --date "$curr"` == "01" ]; then

        # pad the end of the last month
        if [ `$date_cmd +%a --date "$curr -1 day"` != "Sun" ] && [ $curr != $startDate ]; then

            # day in the week
            ndays=`$date_cmd +%u --date "$curr"`
            
            # loop from last day to the end of the week
            for i in $(seq $ndays 7); do 
                printf "|$emptydays" >> "$outputFile"
            done
            # close the last column
            printf "|" >> "$outputFile"
            
        fi

        # start a new month
        printf "  \n" >> "$outputFile"
        printf "  \n" >> "$outputFile"
        printf "$monthHeadingLvl %s\n" "`$date_cmd +"$monthHeadingFormat" --date "$curr"`" >> "$outputFile"

        printf "| $hWeek | $hMon | $hTue | $hWed | $hThu| $hFri | $hSat | $hSun |\n" >> "$outputFile"
        printf "|:---:|:---:|:---:|:---:|:---:|:---:|:---:|:---:|\n" >> "$outputFile"
        
        # If the months first week doesnt start on Monday, pad it
        # and print the week number
        if [ `$date_cmd +%a --date "$curr"` != "Mon" ]; then
            # print the week number
            printf "|%s" "`$date_cmd +%W --date "$curr"`" >> "$outputFile"

            # day in the week
            ndays=`$date_cmd +%u --date "$curr"`
            # minus one for padding
            ndays=`echo "$ndays-1" | bc`   
            
            # loop from Monday to the first day of the month
            for i in $(seq 1 $ndays); do 
                printf "|$emptydays" >> "$outputFile"
            done
        fi
    fi

    # start the week row with the week number
    if [ `$date_cmd +%a --date "$curr"` == "Mon" ]; then
        printf "|%s" "`$date_cmd +%W --date "$curr"`" >> "$outputFile"
    fi

    # Main link output - no arguments, only uses global vars
    print_day_wiki_link

    # End the row on Sunday
    if [ `$date_cmd +%a --date "$curr"` == "Sun" ]; then
        printf "|\n" >> "$outputFile"
    fi

    # increment the date by one day
    curr=$( $date_cmd +%Y-%m-%d --date "$curr +1 day" ) 
done

# print the last day and finish the month off
print_day_wiki_link


# pad the end of the last month
if [ `$date_cmd +%a --date "$curr"` != "Sun" ] ; then

    # day in the week
    ndays=`$date_cmd +%u --date "$curr"`
    
    # loop from last day to the end of the week
    for i in $(seq $ndays 7); do 
        printf "|$emptydays" >> "$outputFile"
    done
    # close the last column
    printf "|" >> "$outputFile"
    
fi

echo "You have $countExistingNotes daily notes"

I'm getting an error on this line:

./calendar.sh: 96: ./calendar.sh: function: not found
./calendar.sh: 105: ./calendar.sh: Bad substitution

I'm using Ubuntu 18.04

Insert this as the first line: #!/usr/bin/env bash.