How to convert YYYYMMDDHHMMSS to a date readable by `date`

Question

I have a set of date/time strings in the YYYYMMDDHHMMSS format that I want to convert to something readable by the date utility. Usually, I can do something li

Answer 1

Try this:

echo "20101106213245" | sed -r 's/^.{8}/& /;:a; s/([ :])(..)\B/\1\2:/;ta'

Result:

20101106 21:32:45

• Insert a space after the eighth character
• [label a] After a space or colon and the next two characters, add a colon
• If a replacement was made, goto label a

You want some hyphens, too?

echo "20101106213245" | sed -r 's/^.{4}/&-/;:a; s/([-:])(..)\B/\1\2:/;ta;s/:/-/;s/:/ /'

Result:

2010-11-06 21:32:45

• Insert a hyphen after the fourth character
• [label a] After a hyphen or colon and the next two characters, add a colon
• If a replacement was made, goto label a
• Change the first colon to a hyphen (2010-11:06:21:32:45 -> 2010-11-06:21:32:45)
• Change the next colon to a space (2010-11-06:21:32:45 -> 2010-11-06 21:32:45)