Convert unix timestamps to other format using sed and date #shell #bash #zsh #epoc

convert-epoc-using-sed.md

Convert unix timestamps in a file using sed and date

Replace unix (epoc) timestamp to other format without changing the file, only print the changes

The /e modifier can be dangerous because it runs the resulting string as code. It is basically an eval() wrapped inside a regex engine. Nonetheless, if you know the content of the file, the sed command is one of the shortest to replace unix timestamps in a file.

# default format used by date
$ sed -E 's/([0-9]{10})/echo ""$(date -d @\1)/e' test.txt
Fri Jan 22 14:00:31 2021 my log entry
Fri Jan 22 14:00:32 2021 my log entry
Fri Jan 22 15:24:12 2021 my log entry

# use custom format
$ sed -E 's/([0-9]{10})/echo ""$(date +"%d-%m-%Y %T" -d @\1)/e' test.txt
22-01-2021 14:00:31 my log entry
22-01-2021 14:00:32 my log entry
22-01-2021 15:24:12 my log entry

Using -i the changes are written to the file

$ sed -Ei 's/([0-9]{10})/echo ""$(date +"%d-%m-%Y %T" -d @\1)/e' test.txt
$ cat test.txt
22-01-2021 14:00:31 my log entry
22-01-2021 14:00:32 my log entry
22-01-2021 15:24:12 my log entry

Print current time in epoc

$ date +"%s"

As an example, a test file test.txt is used

$ cat test.txt
1611320431 my log entry
1611320432 my log entry
1611325452 my log entry