Hide

What's this?

commandlinefu.com is the place to record those command-line gems that you return to again and again.

Delete that bloated snippets file you've been using and share your personal repository with the world. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

If you have a new feature suggestion or find a bug, please get in touch via http://commandlinefu.uservoice.com/

Get involved!

You can sign-in using OpenID credentials, or register a traditional username and password.

OpenID
or
Sign in Register

First-time OpenID users will be automatically assigned a username which can be changed after signing in.

Hide

Stay in the loop…

Follow the Tweets.

Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.

» http://twitter.com/commandlinefu
» http://twitter.com/commandlinefu3
» http://twitter.com/commandlinefu10

Subscribe to the feeds.

Use your favourite RSS aggregator to stay in touch with the latest commands. There are feeds mirroring the 3 Twitter streams as well as for virtually every other subset (users, tags, functions,…):

Subscribe to the feed for:

Hide

News

2011-03-12 - Confoo 2011 presentation
Slides are available from the commandlinefu presentation at Confoo 2011: http://presentations.codeinthehole.com/confoo2011/
2011-01-04 - Moderation now required for new commands
To try and put and end to the spamming, new commands require moderation before they will appear on the site.
2010-12-27 - Apologies for not banning the trolls sooner
Have been away from the interwebs over Christmas. Will be more vigilant henceforth.
2010-09-24 - OAuth and pagination problems fixed
Apologies for the delay in getting Twitter's OAuth supported. Annoying pagination gremlin also fixed.
Hide

Tags

Hide

Functions

Hide

Credits

Site by David Winterbottom (user root).

quick and easy way of validating a date format of yyyy-mm-dd and returning a boolean

Terminal - quick and easy way of validating a date format of yyyy-mm-dd and returning a boolean
echo 2006-10-10 | grep -c '^[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]$'
2009-05-11 22:18:43
User: rez0r
Functions: echo grep
-1
Up
Down
quick and easy way of validating a date format of yyyy-mm-dd and returning a boolean

Quick and easy way of validating a date format of yyyy-mm-dd and returning a boolean, the regex can easily be upgraded to handle "in betweens" for mm dd or to validate other types of strings, ex. ip address.

Boolean output could easily be piped into a condition for a more complete one-liner.

Add to favourites | Report as malicious

Alternatives

There are 2 alternatives - vote for the best!

Terminal - Alternatives
if date -d 2006-10-10 >> /dev/null 2>&1; then echo 1; else echo 0; fi
2013-01-10 10:35:15
User: SteveGoossens
Functions: date echo
Tags: date validation
0
Up
Down
quick and easy way of validating a date format of yyyy-mm-dd and returning a boolean

On CentOS at least, date returns a boolean for the common date string formats, including YYYY-MM-DD. In the sample output, you can see various invalid dates returning 0 whereas a simple regex check would return 1 for the invalid dates.

-d, --date=STRING display time described by STRING, not `now'

The version of date on OS X does not appear to have this same option.

Show sample output | Comments (0) | Add to favourites | Report as malicious

Know a better way?

If you can do better, submit your command here.

What others think

You can reduse repetitious typing using 1 of the following commands and achieve the same result :).

echo 2006-10-10 |egrep -c '^[0-9]{4}-[0-9]\{2\}-[0-9]\{2\}'

OR

echo 2006-10-10 |egrep -c '^[0-9]{4}-[0-9]{2}-[0-9]{2}'

Comment by scifisamurai 210 weeks and 5 days ago

Aghh, correction - the 1st line should have been:

echo 2006-10-10 |grep -c '^[0-9]\{4\}-[0-9]\{2\}-[0-9]\{2\}'

I wish commandlinefu had a delete option for one's own posts/comments to clean up one's own typos.

Comment by scifisamurai 210 weeks and 5 days ago

nice:)

Comment by rez0r 210 weeks and 3 days ago

Your point of view

You must be signed in to comment.

Related sites and podcasts