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.
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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,…):
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Wow, didn't really expect you to read this far down. The latest iteration of the site is in open beta. It's a gentle open beta-- not in prime-time just yet. It's being hosted over at UpGuard (link) and you are more than welcome to give it a shot. Couple things:
shell order of operation example which calculates:
x = number of physical CPU's
y = number of cores per CPU
2(x * y) + 1 = CPU load limit
seed the random number generator,
find all matches in a file
put all matches from the capture group into an array
return a random element from the array
The only command-line version of this task I could come up with that properly handles UTF-8 input, too. (Yes, I know how crazy it is to have UTF-8 with HTML entity escapes, but that stuff exists... sadly...; Just check Twitter.)
Returns the current price of a troy ounce of gold, in USD. Requires the "jq" JSON parser.
Hold 'Ctrl' + 'Alt' key while selecting rectangular text area of the screen with
left mouse button.
Should work in any terminal screen (xterm, konsole, ...) under X, if not
then try with 'Ctrl' + 'Shift' + 'Alt' or two-combination of these.
I often have to google this so I put it here for quick reference.
In Thunderbird open the settings for your email account, mark the checkbox for 'Attach the signature from a file instead' and use the filename '~/mailsignature.txt'
Now every time when you open a terminal you see the fortune displayed in the terminal and the mail signature gets regenerated.
See "Parameter Expansion" in the bash manpage. They refer to this as "Use Alternate Value", but we're including the var in the at alternative.
The read command reads input and puts it into a variable. With -i you set an initial value. In this case I used a known environment variable.
In this case the current user has proxy variable set which allows access to the rpm on the internet but needs root privs to install it.
Running sudo -E preserves the current user proxy var and allows the rpm install to be executed with sudo.
If this matches any files on your web server expect to find allot of malware spread throughout your server folders. Seems to target wordpress sites. Be sure to check your themes/theme-name/header.php files manually for various redirect scripting usually in the line right above the close head tag.
Someone quoted Pooh in an init script. Let's see it!
(Probably only works on Debian & friends)
You can search for CVEs at https://security-tracker.debian.org/tracker/ or use --report to get full links. This can be added to cron, but unless you're going to do manual patches, you'd just be torturing yourself.
This command will display the file, but you can change 'cat' to anything else
(type 'n' when prompted to cancel the command or anything else to proceed).
Some hints for newbies:
to make 'bar' function annihilated.
For permanent usage you can put this (bar) function in your .bashrc (for bash) or in .profile (for sh).
you can get all new inserted functions in .bashrc (so the function 'bar'
or whatever name you choose) immediately available.
tcpdump into file with date format for wireshark
capture trafic for wireshark from spesific eth interface
This command validates if exist any character different in 0-255 and dot.
If any characters different is typed the error menssage is showing.
Print out your age in days in binary.
Today's my binary birthday, I'm 2^14 days old :-)
This command does bash arithmatic $(( )) on two dates:
Today: $(date +%s)
Date of birth: $(date +%s -d YYYY-MM-DD)
The dates are expressed as the number of seconds since the Unix epoch (Jan 1970),
so we devide the difference by 86400 (seconds per day).
Finally we pipe "obase=2; DAYS-OLD" into bc to convert to binary.
(obase == output base)
Often you run a command, but afterwards you're not quite sure what it did.
By adding this prefix/suffix around [COMMAND], you can list any files that were modified.
Take a nanosecond timestamp: YYYY-MM-DD HH:MM:SS.NNNNNNNNN
date "+%F %T.%N"
Find any files that have been modified since that timestamp:
find . -newermt "$D"
This command currently only searches below the current directory.
If you want to look elsewhere change the find parameter, e.g.
find /var/log . -newermt "$D"
This lists all files modified after calling some command using a temporal anchor.