Bash script to compare a particular line in two different files, and compare dates

Question

I would like to compare line number 13 in two different files. That line contains date in the format: "Nov 8 00:46:57 2021 GMT"

I want to compare these two dates, and check which is less or greater than the other. Can someone please help me with this.

user1984 · Answer 1 · 2021-09-20T21:35:41.557

1

# Reads line 13 of file1.txt into date1
date1=$(awk 'NR==13' file1.txt)
# Reads line 13 of file2.txt into date2
date2=$(awk 'NR==13' file2.txt)

# converts date to seconds since the Epoch in Linux
date1=$(date -d "$date1" +%s)
date2=$(date -d "$date2" +%s)

if (( date1 >= date2 )); then
  echo "Date in file1.txt is greater or equal"
else
  echo "Date in file2.txt is greater"
fi

edited Sep 20 '21 at 21:35

answered Sep 20 '21 at 21:11

user1984

5,990
2
13
32

1

`awk 'NR == 13' file1.txt` is shorter and `awk 'NR == 13 {print; exit}' file1.txt` might be more “efficient”. (Also `if ((date1 >= date2)); then ...` might be easier to read.) – Andrej Podzimek Sep 20 '21 at 21:23
Fully agree. Thanks you for sharing. – user1984 Sep 20 '21 at 21:24

score 0 · Answer 2 · answered Sep 20 '21 at 21:15

0

13a and 13b are your file names:

iso8601-13() {
    date -d "`head -13 "$1" | tail -n 1`" --iso-8601=seconds
}

if [[ `iso8601-13 13a` < `iso8601-13 13b` ]] ; then
    echo 13a is earlier
fi

answered Sep 20 '21 at 21:15

MarJoh

66
4

Bash script to compare a particular line in two different files, and compare dates

2 Answers2