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View all date formats, Quick Reference Help Alias

Terminal - View all date formats, Quick Reference Help Alias
alias dateh='date --help|sed -n "/^ *%%/,/^ *%Z/p"|while read l;do F=${l/% */}; date +%$F:"|'"'"'${F//%n/ }'"'"'|${l#* }";done|sed "s/\ *|\ */|/g" |column -s "|" -t'
2010-04-21 01:22:18
User: AskApache
Functions: alias column date read sed
21
View all date formats, Quick Reference Help Alias

If you have used bash for any scripting, you've used the date command alot. It's perfect for using as a way to create filename's dynamically within aliases,functions, and commands like below.. This is actually an update to my first alias, since a few commenters (below) had good observations on what was wrong with my first command.

# creating a date-based ssh-key for askapache.github.com

ssh-keygen -f ~/.ssh/`date +git-$USER@$HOSTNAME-%m-%d-%g` -C 'webmaster@askapache.com' # /home/gpl/.ssh/git-gplnet@askapache.github.com-04-22-10

# create a tar+gzip backup of the current directory

tar -czf $(date +$HOME/.backups/%m-%d-%g-%R-`sed -u 's/\//#/g' <<< $PWD`.tgz) . # tar -czf /home/gpl/.backups/04-22-10-01:13-#home#gpl#.rr#src.tgz .

I personally find myself having to reference

date --help

quite a bit as a result. So this nice alias saves me a lot of time. This is one bdash mofo. Works in sh and bash (posix), but will likely need to be changed for other shells due to the parameter substitution going on.. Just extend the sed command, I prefer sed to pretty much everything anyways.. but it's always preferable to put in the extra effort to go for as much builtin use as you can. Otherwise it's not a top one-liner, it's a lazyboy recliner.

Here's the old version:

alias dateh='date --help|sed "/^ *%%/,/^ *%Z/!d;s/ \+/ /g"|while read l;do date "+ %${l/% */}_${l/% */}_${l#* }";done|column -s_ -t'

This trick from my [ http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html bash_profile ]

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Terminal - Alternatives

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What others think

I just use man date, as it explains the difference between e and f and u and w and U, V and W and others that come up identical with this command at certain moments.

man date |grep %
Comment by houghi 239 weeks and 3 days ago

I like this as it works with current time

Comment by oernii2 239 weeks and 3 days ago

Why did you duplicate the sample output? Can you edit it out of your main description?

Comment by SuperJediWombat 239 weeks and 3 days ago

@SuperJedi

got it.

@houghi

I upgraded the script to make it better than man, thanks for the push. Now save some keystrokes.

Comment by AskApache 239 weeks and 1 day ago

I prefer this version with less whitespace and line wrapping:

alias dateh='date --help|sed -n "/^ *%%/,/^ *%Z/p"|while read l;do date "+ %${l/% */}:%t${l/% */}%n%t%t${l#* }";done'

It also eliminates some odd quote placement and escaping in the original.

Comment by dennisw 239 weeks and 1 day ago

Your point of view

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