This type of join is clearly documented in the bash manual. Only the first character of IFS is used for the delimiter.

This script can be used to download enclosed files from a RSS feed. For example, it can be used to download mp3 files from a podcasts RSS feed.

An entirely shell-based solution (should work on any bourne-style shell), more portable on relying on the rename command, the exact nature of which varies from distro to distro.

Bash's history expansion character, "!", has many features, including "!:" for choosing a specific argument (or range of arguments) from the history. The gist is any number after !: is the number of the argument you want, with !:1 being the first argument and !:0 being the command. See the sample output for a few examples. For full details search for "^HISTORY EXPANSION" in the bash(1) man page.

 Note that this version improves on the previous function in that it handles arguments that include whitespace correctly.

Simple and easy to remember, if it already exists then it just ignores it.

[Click the "show sample output" link to see how to use this keystroke.]

Meta-p is one of my all time most used and most loved features of working at the command line. It's also one that surprisingly few people know about. To use it with bash (actually in any readline application), you'll need to add a couple lines to your .inputrc then have bash reread the .inputrc using the bind command:

  I first learned about this feature in tcsh. When I switched over to bash about fifteen years ago, I had assumed I'd prefer ^R to search in reverse. Intuitively ^R seemed better since you could search for an argument instead of a command. I think that, like using a microkernel for the Hurd, it sounded so obviously right fifteen years ago, but that was only because the older way had benefits we hadn't known about.

  I think many of you who use the command line as much as I do know that we can just be thinking about what results we want and our fingers will start typing the commands needed. I assume it's some sort of parallel processing going on with the linguistic part of the brain. Unfortunately, that parallelism doesn't seem to work (at least for me) with searching the history. I realize I can save myself typing using the history shortly after my fingers have already started "speaking". But, when I hit ^R in Bash, everything I've already typed gets ignored and I have to stop and think again about what I was doing. It's a small bump in the road but it can be annoying, especially for long-time command line users. Usually M-p is exactly what I need to save myself time and trouble.

  If you use the command line a lot, please give Meta-p a try. You may be surprised how it frees your brain to process more smoothly in parallel. (Or maybe it won't. Post here and let me know either way. ☺)

This gets the Nth argument in the last line of your history file. This is useful where history is being written after each command, and you want to use arguments from the previous command in the current command, such as when doing copies/moving directories etc.

I wrote this after getting irritated with having to continually type in long paths/arguments.

You could also use $_ if all you want is the last argument.

url can be like any one of followings:

If url mismatching, whole url will be returned.

set BLOCK to "title" or any other HTML / RSS / XML tag and curl URL to get everything in-between e.g. some text

If you want avoid to be annoyed when playing your favourite video files with your video player, first run this command to stash wrong files (and test tricks to play these wrong files).

Compares the md5 checksums of the contents of two directories, outputting the checksum and filename where any files differ. Shows only the file name, not the full path.

Run "ps -x" (process status) in the background every hour (in this example).

The outputs of both "nohup" and "ps -x" are sent to the e-mail (instead of nohup.out and stdout and stderr).

If you like it, replace "ps -x" by the command of your choice, replace 3600 (1 hour) by the period of your choice.

You can run the command in the loop any time by killing the sleep process. For example

2925 ? S 0:00.00 sh -c unzip E.zip >/dev/null 2>&1

11288 ? O 0:00.00 unzip E.zip

25428 ? I 0:00.00 sleep 3600

14346 pts/42- I 0:00.01 bash -c while true; do ps -x | mail pascalv; sleep 3600; done

643 pts/66 Ss 0:00.03 -bash

14124 pts/66 O+ 0:00.00 ps -x

You have mail in /mail/pascalv

Compute the md5 checksums for the contents of two mirrored directories, then sort and diff the results. If everything matches, nothing is returned. Otherwise, any checksums which do not match, or which exist in one tree but not the other, are returned. As you might imagine, the output is useful only if no errors are found, because only the checksums, not filenames, are returned. I hope to address this, or that someone else will!

Retrieved from:

https://en.wikipedia.org/wiki/Fork_bomb

More info:

http://stackoverflow.com/questions/991142/how-does-this-bash-fork-bomb-work

Puts a splash of color in your access logs. IP addresses are gray, 200 and 304 are green, all 4xx errors are red. Works well with e.g. "colorize access_log | less -R" if you want to see your colors while paging.

Use as inspiration for other things you might be tailing, like syslog or vmstat

Usage:

bash output is inserted into the clipboard, then mousepad is started and the clipboard content is pasted. xsel and xdotool needs to be installed. Instead of the mousepad any other editor can be used. I've successfully tested the Sublime Text Editor and it opens a new tab for each new paste. Check Sample output for a usage example. This command is originated from here - http://goo.gl/0q9UT4

Sometimes in a script you want to make sure that a directory is in the path, and add it in if it's not already there. In this example, $dir contains the new directory you want to add to the path if it's not already present.

There are multiple ways to do this, but this one is a nice clean shell-internal approach. I based it on http://stackoverflow.com/a/1397020.

You can also do it using tr to separate the path into lines and grep -x to look for exact matches, like this:

which I got from http://stackoverflow.com/a/5048977.

Or replace the "echo | tr" part with a shell parameter expansion, like

which I got from http://www.commandlinefu.com/commands/view/3209/.

There are also other more regex-y ways to do it, but I find the ones listed here easiest to follow.

Note some of this is specific to the bash shell.

use the shell default positional parameter syntax ${X:-default} in lieu of testing.

Piping ps into grep is mostly useless: ps has its own filter options like -u and -C