Calculate days on which Friday the 13th occurs

for i in {2018..2022}-{01..12}-13; do date --date $i +"%Y %B %w" | sed '/[^5]$/d; s/ 5*$//'; done
Alter the years in the first brace expansion to select your year range. Modify date format to your liking but leave " %w" at the end.
Sample Output
2018 April
2018 July
2019 September
2019 December
2020 March
2020 November
2021 August
2022 May

0
2018-07-09 15:47:39

4 Alternatives + Submit Alt

  • I removed the dependency of the English language Show Sample Output


    5
    for y in $(seq 1996 2018); do echo -n "$y -> "; for m in $(seq 1 12); do NDATE=$(date --date "$y-$m-13" +%w); if [ $NDATE -eq 5 ]; then PRINTME=$(date --date "$y-$m-13" +%B);echo -n "$PRINTME "; fi; done; echo; done
    ginochen · 2018-06-25 09:20:57 1
  • Friday is the 5th day of the week, monday is the 1st. Output may be affected by locale. Show Sample Output


    2
    for i in {2018..2025}-{01..12}-13; do [[ $(date --date $i +"%u" | grep 5) != 5 ]] || echo "$i Friday the 13th"; done
    test666v2 · 2018-07-10 21:31:02 0
  • Simply change the years listed in the first seq, and it will print out all the months in that span of years that have Friday the 13ths in them. Show Sample Output


    1
    for y in $(seq 1996 2018); do echo -n "$y -> "; for m in $(seq 1 12); do NDATE=$(date --date "$y-$m-13" +%A); if [ $NDATE == 'Friday' ]; then PRINTME=$(date --date "$y-$m-13" +%B);echo -n "$PRINTME "; fi; done; echo; done
    suspenderguy · 2018-06-13 20:11:46 0
  • Removed grep and simplified if statement. -- Friday is the 5th day of the week, monday is the 1st. Output may be affected by locale. Show Sample Output


    0
    for i in {2018..2025}-{01..12}-13; do [[ $(date --date $i "+%u") == 5 ]] && echo "$i Friday the 13th"; done
    cpqlinux · 2018-07-30 15:54:24 0

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