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

date doesn't allow "YYYYMMDDHHMMSS", but it does "YYYYMMDD HH:MM:SS", so:

D="20100101123456"
date -d "${D:0:8} ${D:8:2}:${D:10:2}:${D:12:2}"

Answer 2

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)

Answer 3

What's with all of these regular expression answers? The date(1) tool has the ability to use strftime() style date formatting... an an example of converting one date type to another:

$ date -j -f "%Y%m%d%H%M%S" "20100101123456" "+%Y-%m-%d %H:%M:%S"
2010-01-01 12:34:56

So if it's not in the format you want, convert it like that and then use it. If you just want to set it, you can simply do:

$ date -f "%Y%m%d%H%M%S" "20100101123456"

Answer 4

If the format is totally fixed, you could just do it within bash, chopping up the string:

d=20100101123456
pretty_date="${d:0:4}-${d:4:2}-${d:6:2} ${d:8:2}:${d:10:2}:${d:12:2}"
# 2010-01-01 12:34:56
...

I wouldn't bother trying to use regex - like you said, the pattern gets ugly fast. A lot of repetition of ([0-9]{4}), even with extended or perl regex. Or you could be flexible and just match .; no verification.

Answer 5

 sed -ne 's/\(....\)\(..\)\(..\)\(..\)\(..\)\(..\)/\1-\2-\3 \4:\5:\6/p'

I admit it'S a mouthful. All the .'s should optimally be [0-9] or \d, though I don't remember if sed supports the latter.

Answer 6

Either busybox date or bsd date accept a description of the input format.

Busybox is a GNU small utility, easy to install.

The bsd format has been covered in another answer, so here is busybox:

$ busybox date -D "%Y%m%d%H%M%S" -d "20100101123456" +'%Y-%m-%d %H:%M:%S'
2010-01-01 12:34:56