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/
You can sign-in using OpenID credentials, or register a traditional username and password.
First-time OpenID users will be automatically assigned a username which can be changed after signing in.
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.
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:
Back up /etc directory with a name based on the current date and the hostname of the machine, then chown the file for the current user for use.
On the Mac, the 'ls' function can sort based on month/day/time, but seems to lack ability to filter on the Year field (#9 among the long listed fields). The sorted list continuously increases the 'START' year for the most recently accessed set of files. The final month printed will be the highest month that appeared in that START year. The command does its magic on the current directory, and suitably discards all entries that are themselves directories. If you expect files dating prior to 2002, change the START year accordingly.
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.
Format of the response: [-]HH:mm
Appends the input file with the date format YYYY-MM-DD.bak. Also runs silently if you remove the -v on the cp at the end of the function.
Fake system time before running any command.
Choosing your year and month. You only need the gnu date command and bash. desiredDay of the week is (1..7); 1 is Monday.
If you want desiredDay of week (0..6); 0 is Sunday
desiredDay=6; year=2012; month=5; n=0; while [ $(date -d "$year-$((month+1))-1 - $n day" "+%w") -ne $desiredDay ]; do n=$((n+1)); done; date -d "$year-$((month+1))-1 - $n day" "+%x"
If your locale has Monday as the first day of the week, like mine in the UK, change the two $7 into $6
This is a little trickier than finding the last Sunday, because you know the last Sunday is in the first position of the last line. The trick is to use the NF less than or equal to 7 so it picks up all the lines then grep out any empty lines.
The command renames all files in a certain directory. Renaming them to their date of creation using EXIF. If you're working with JPG that contains EXIF data (ie. from digital camera), then you can use following to get the creation date instead of stat.
* Since not every file has exif data, we want to check that dst is valid before doing the rest of commands.
* The output from exif has a space, which is a PITA for filenames. Use sed to replace with '-'.
* Note that I use 'echo' before the mv to test out my scripts. When you're confident that it's doing the right thing, then you can remove the 'echo'... you don't want to end up like the guy that got all the files blown away.
Get the time since epoch. Useful when working with commands and logs which use this format.
Gets any date since today. Other examples of recognized expressions are "2 years 4 days ago", "7 months" (in the future), "next Sunday", "yesterday", "tomorrow", etc.
Convert readable date/time with `date` command
date -ud @1320198157
uses the -u switch for UTC
Another way could be
echo $(($(date -ud "00:29:36" +%s)%86400))
The same with colors
This command will show the current GMT time using HTTP. This might be useful if you just want to know what's the current human-readable and accurate-enough time, without changing the system time, using a simple command that would work regardless of the availability of NTP.
Note: To get a quicker and more accurate response, replace google.com with your local NTP server.
Also can be used as an alternative to the "htpdate" program: