commandlinefu.com is the place to record those command-line gems that you return to again and again.
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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:
F filters using first word. $F - 2nd, and so on.
Not really better - just different ;)
There's probably a really simple solution out there somewhere...
If you are in an environment where you don't have the base64 executable or MIME tools available, this can be very handy for salvaging email attachments when the headers are mangled but the encoded document itself is intact.
Fun idea! This one adds seconds and keeps running on the same line. Perl's probably cheating though. :)
This command turns a multi-line file into a single line joined with <SOMETEXT>. To skip blank lines, use:
perl -pe '(eof()||s/^\s*$//)||s/\n/<SOMETEXT>/g' file.txt
I used this to mass install a lot of perl stuff. Threw it together because I was feeling *especially* lazy. The 'perl' and the 'module' can be replaced with whatever you like.
In this way it doesn't have problems with filenames with spaces.
Today I needed a way to print various character classes to use as input for a program I was writing. Also a nice way to visualize character classes.
Safe for whitespaces in names.
Parse the output of git status.
Once the line '# Changed but not updated:' has passed print every last part of the line if it exists on disk.
**NOTE** Tekhne's alternative is much more succinct and its output conforms to the files actual contents rather than with white space removed
My command on the other hand uses bash process substitution (and "Minimal" Perl), instead of files, to first remove leading and trailing white space from lines, before diff'ing the streams. Very useful when differences in indentation, such as in programming source code files, may be irrelevant
This deals nicely with filenames containing special characters and can deal with more files than can fit on a commandline. It also avoids spawning du.
Perl variant of echo several blank lines command
Function: char * crypt (const char *key, const char *salt)
The crypt function takes a password, key, as a string, and a salt character array which is described below, and returns a printable ASCII string which starts with another salt. It is believed that, given the output of the function, the best way to find a key that will produce that output is to guess values of key until the original value of key is found.
The salt parameter does two things. Firstly, it selects which algorithm is used, the MD5-based one or the DES-based one. Secondly, it makes life harder for someone trying to guess passwords against a file containing many passwords; without a salt, an intruder can make a guess, run crypt on it once, and compare the result with all the passwords. With a salt, the intruder must run crypt once for each different salt.
For the MD5-based algorithm, the salt should consist of the string $1$, followed by up to 8 characters, terminated by either another $ or the end of the string. The result of crypt will be the salt, followed by a $ if the salt didn't end with one, followed by 22 characters from the alphabet ./0-9A-Za-z, up to 34 characters total. Every character in the key is significant.
For the DES-based algorithm, the salt should consist of two characters from the alphabet ./0-9A-Za-z, and the result of crypt will be those two characters followed by 11 more from the same alphabet, 13 in total. Only the first 8 characters in the key are significant.
usefull for posts via wget
All with only one pipe. Should be much faster as well (sort is slow). Use find instead of ls for recursion or reliability.
Edit: case insensitive
This version works on an AIX system on which I have very limited permissions. The other version fails with "Can't open file /usr/opt/perl588/lib/site_perl/5.8.8/aix/auto/DBI/.packlist".
This will show you any links that a command follows (unlike 'file -L'), as well as the ultimate binary or script.
Put the name of the command at the very end; this will be passed to perl as the first argument.
For obvious reasons, this doesn't work with aliases or functions.
Replace DOS character ^M with newline using perl inline replace.
Works only if modules are installed "the right way"
This will list all symlinks that are directories under the current directory. This will help you distinguish them from regular files.