beer planet » key http://beerpla.net where things have nothing to do with beer - tutorials, tips, how-tos, thoughts, hacks, and other techy nonsense Thu, 17 May 2012 22:50:53 +0000 en hourly 1 http://wordpress.org/?v=3.3.2 Mastering The Linux Shell – Bash Shortcuts Explained (Now With Cheat Sheets)http://beerpla.net/2008/12/22/mastering-the-linux-shell-bash-shortcuts-explained/ http://beerpla.net/2008/12/22/mastering-the-linux-shell-bash-shortcuts-explained/#comments Mon, 22 Dec 2008 19:46:05 +0000 Artem Russakovskii http://beerpla.net/2008/12/22/getting-around-bash-bash-shortcuts/ imageDuring my day-to-day activities, I use the Bash shell a lot. My #1 policy is to optimize the most frequently used activities as much as possible, so I’ve compiled these handy bash shortcuts and hints (tested in SecureCRT on Windows and Konsole on Linux). The article only touches on the default bash mode – emacs, not vi. If you haven’t specifically assigned your shell mode to vi (set –o vi), you’re almost certainly using the emacs mode. Learn these and your shell productivity will skyrocket, I guarantee it.

Update #1: In response to a few people saying this list is too short and “[he] could've added something to it, to atleast make it look longer” (quote from one of Stumbleupon
...
Read the rest of this article »

]]> imageDuring my day-to-day activities, I use the Bash shell a lot. My #1 policy is to optimize the most frequently used activities as much as possible, so I’ve compiled these handy bash shortcuts and hints (tested in SecureCRT on Windows and Konsole on Linux). The article only touches on the default bash mode – emacs, not vi. If you haven’t specifically assigned your shell mode to vi (set –o vi), you’re almost certainly using the emacs mode. Learn these and your shell productivity will skyrocket, I guarantee it.

Update #1: In response to a few people saying this list is too short and “[he] could've added something to it, to atleast make it look longer” (quote from one of Stumbleupon reviewers), I want to clarify something. I deliberately did not include every single bash shortcut there is. I included what I personally thought were the best and most useful commands. I did not want to make the list too cluttered and wanted the cheat sheet to fit on one page without going to a smaller font size.

image 

Download Version 1.3 (03/22/12):

And, for quick reference, here's the ugly html version:


Keyboard shortcut

Action

Navigation

Ctrl-A

Go to the beginning of the line (note that if you use GNU screen, you can use the Home button to do this, especially considering that Ctrl-A is a special control character in screen).

Ctrl-E

Go to the end of the line (note that if you use GNU screen, you can use the End button to do this).

Alt-B (or ESC, left arrow)

Jump back one word using a non-alphanumeric character as delimiter.

Alt-F (or ESC, right arrow)

Jump forward one word using a non-alphanumeric character as delimiter.

Ctrl-PGUP or Shift-PGUP

This may or may not work, and it works differently on different console apps. It will either scroll up one line at a time, 1 page at a time, or it may not work at all. I'm inclined to think it's not a bash shortcut at all.

Ctrl-PGDN or Shift-PGDN

Same as the above but scrolling is done in the opposite direction.

Up/Down

Previous/Next command in history. This one is way too obvious but I'm including it for completeness.

Ctrl-R

History search. For example, Ctrl-R svn Ctrl-R Ctrl-R … will cycle through all recently run commands with the ‘svn’ in them. It is one of the most useful shortcuts in bash.

Ctrl-O

Takes whatever line was after the line you selected with Ctrl-R and makes it your next command.

Command Line Manipulation

Ctrl-W

Cut one word backwards using white space as delimiter.

Alt-BACKSPACE

Cut one word backwards using a non-alphanumeric character as delimiter (different from Ctrl-W, for example, abc;bcd will cut to abc;).

Ctrl-K

Cut everything forward to end of line.

Ctrl-U

Cut everything backwards to beginning of line.

Ctrl-T

Transpose the current character with the previous one. I almost never use this. Never mind, I never use it, but someone might find it useful.

Alt-T

Transpose the word at cursor with the one before cursor. In other words, swap them around.

Ctrl-Y

Paste whatever was cut by the last cut command.

Ctrl-V

Insert the next character literally. For example, Ctrl-V TAB inserts the actual TAB character. This shortcut is often misunderstood because of mistyping Ctrl-V and not realizing what it does.

Ctrl-_

Undo the last command. Don’t forget – it’s Ctrl-Shift-MINUS, not Ctrl-MINUS.

Alt-R

Revert all changes to current line. Very useful if you accidentally modify a command in history.

Alt-U/Alt-L/Alt-C

Uppercase/lowercase/capitalize from cursor to end of word and move cursor past end of word.

Terminal control

Ctrl-L

Clear screen while keeping whatever is already typed in the command line intact.

Ctrl-S

Suspend currently running terminal.

Ctrl-Q

Unsuspend the terminal suspended by Ctrl-S. You need to be aware of this shortcut because 99% of the time you’ve accidentally pressed Ctrl-S and need to undo its effects.

Ctrl-Z

Suspend the currently running process (usually followed by bg to resume it in the background or fg to resume in the foreground).

TAB

Autocomplete. Start typing, then hit TAB. You will either get a list of possible completion values (2 TABs needed) or the only choice will be filled in (only 1 TAB is needed). This shortcut is quite obvious and well known, so I put it at the bottom of the list.

Tip: By the way, as duly noted in the comments, all of these tricks work on the mysql command line, so you can, for example, ctrl-R through your previously executed mysql commands.

Hope you guys will find this list helpful. I think it is relatively complete, but feel free to add any omissions.

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]]> http://beerpla.net/2008/12/22/mastering-the-linux-shell-bash-shortcuts-explained/feed/ 32 Debugging Weird sshd Connection Problems + What Happens When You Stop sshdhttp://beerpla.net/2008/08/15/debugging-weird-sshd-connection-problems-what-happens-when-you-stop-sshd/ http://beerpla.net/2008/08/15/debugging-weird-sshd-connection-problems-what-happens-when-you-stop-sshd/#comments Fri, 15 Aug 2008 16:14:53 +0000 Artem Russakovskii http://beerpla.net/2008/08/15/debugging-weird-sshd-connection-problems-what-happens-when-you-stop-sshd/ So the other day I was setting up public key authentication for one of my users, which is usually very straightforward: generate a private/public key pair, stick the private key into user's .ssh dir, set dir permissions to 0700, private key permissions to 0600, stick the public key into the authorized_keys file on the server, and the job's done. However, this time, no matter what I was doing, the public key was being rejected or ignored and the system was moving on to the keyboard-interactive authentication.

Debugging on the client side with -v didn't help much:

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artem@DeathStar:~/svn/b2/Fetch/LinkChecker> ssh -v
...
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]]> So the other day I was setting up public key authentication for one of my users, which is usually very straightforward: generate a private/public key pair, stick the private key into user's .ssh dir, set dir permissions to 0700, private key permissions to 0600, stick the public key into the authorized_keys file on the server, and the job's done. However, this time, no matter what I was doing, the public key was being rejected or ignored and the system was moving on to the keyboard-interactive authentication.

Debugging on the client side with -v didn't help much:

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artem@DeathStar:~/svn/b2/Fetch/LinkChecker> ssh -v monkey@192.168.1.30
OpenSSH_4.6p1, OpenSSL 0.9.8e 23 Feb 2007
...
lots of boring shit
...
debug1: Found key in /home/artem/.ssh/known_hosts:1
debug1: ssh_rsa_verify: signature correct
...
more boring shit
...
debug1: Authentications that can continue: publickey,keyboard-interactive
debug1: Next authentication method: publickey
debug1: Offering public key:
debug1: Authentications that can continue: publickey,keyboard-interactive
debug1: Offering public key:
debug1: Authentications that can continue: publickey,keyboard-interactive
debug1: Offering public key: /home/artem/.ssh/id_rsa
debug1: Authentications that can continue: publickey,keyboard-interactive
debug1: Trying private key: /home/artem/.ssh/id_dsa
debug1: Next authentication method: keyboard-interactive
Password:

After breaking my head over possible reasons why the pile of junk that thinks it's smarter than me next to my feet doesn't work, kicking it a few times, and observing the same result, I turned to debugging the ssh daemon itself – sshd.

  • The -d option disables the daemon mode and enables debug mode, in which only 1 connection is accepted for the lifetime of the server, after which it simply quits.
  • -dd simply enables a more detailed output.
  • -e switches this debug output from a log file to STDOUT.

However, to free up port 22, I had to stop the daemon that was already running, or else a "Bind to port 22 on 0.0.0.0 failed: Address already in use." error appeared (duh). An interesting question though, especially for people doing this to remote boxes, what happens when one stops sshd? Ever thought of doing that but instead ran over to your mommy crying like a little girl? Well, fear no more, because I'll tell you exactly what happens:

  1. New users will have their connection refused.
  2. Your own connection will not be interrrupted. sshd works by spawning a new instance of itself for every incoming connection, so your own sshd process will stay in memory.

So where was I?

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Authentication refused: bad ownership or modes for directory /home/monkey
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Failed publickey for monkey from 192.168.1.30 port 56287 ssh2

AhA!! (emphasis on the last 'a'). What have we here?

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artem@DeathStar:~> cd /home/
artem@DeathStar:/home/> l
drwxrwx--- 29 monkey  users 4096 2008-08-06 23:14 monkey/
 
DeathStar:/home/ # chmod 755 monkey
drwxr-xr-x 29 monkey  users 4096 2008-08-06 23:14 monkey/
 
artem@DeathStar:~/svn/b2/Fetch/LinkChecker> ssh -v monkey@192.168.1.30
OpenSSH_4.6p1, OpenSSL 0.9.8e 23 Feb 2007
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to 192.168.1.30 [192.168.1.30] port 22.
debug1: Connection established.
debug1: identity file /home/artem/.ssh/id_rsa type 1
debug1: identity file /home/artem/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_4.6
debug1: match: OpenSSH_4.6 pat OpenSSH*
...

Connection established, all systems are go, the key has been accepted.

Inspired by http://linux.derkeiler.com/Mailing-Lists/Fedora/2005-08/1105.html

P.S. Don't forget to /etc/init.d/sshd start. ;)

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]]> http://beerpla.net/2008/08/15/debugging-weird-sshd-connection-problems-what-happens-when-you-stop-sshd/feed/ 1 Some Useful vim Commands – My vim Cheatsheethttp://beerpla.net/2008/04/09/some-useful-vim-commands-my-vim-cheatsheet/ http://beerpla.net/2008/04/09/some-useful-vim-commands-my-vim-cheatsheet/#comments Thu, 10 Apr 2008 04:07:24 +0000 Artem Russakovskii http://beerpla.net/?p=330 [WORK IN PROGRESS] Here is a list of commands that I use every day with vim, in no particular order. Out of a billion possible key combinations, I found these to be irreplaceable and simple enough to remember.

     

    *

    search for the word under cursor (to the end of the file)

    #

    search for the word under cursor (to the top of the file)

    ctrl-p,ctrl-n

    suggest (p)revious or (n)ext autocomplete from the list of existing keywords in the file or included files (!).

    :go NNN

    go to byte NNN

    .

    redo last command

    /SEARCH TERM

    search document for SEARCH TERM

    :%s/FOO/BAR/gci

    replace FOO with BAR (g)lobally, case (i)insensitively, and asking for (c)onfirmation

...
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]]> [WORK IN PROGRESS] Here is a list of commands that I use every day with vim, in no particular order. Out of a billion possible key combinations, I found these to be irreplaceable and simple enough to remember.

     

    *

    search for the word under cursor (to the end of the file)

    #

    search for the word under cursor (to the top of the file)

    ctrl-p,ctrl-n

    suggest (p)revious or (n)ext autocomplete from the list of existing keywords in the file or included files (!).

    :go NNN

    go to byte NNN

    .

    redo last command

    /SEARCH TERM

    search document for SEARCH TERM

    :%s/FOO/BAR/gci

    replace FOO with BAR (g)lobally, case (i)insensitively, and asking for (c)onfirmation

    n (N)

    next (previous) search result

    %

    find and jump to a matching brace or parenthesis

    u

    undo

    ctrl-r

    redo

    r CHAR

    replace character under curson with CHAR

    i

    start editing before current character

    I

    start editing in the beginning of current line

    a

    start editing after current character

    A

    start editing at the end of current line

    o

    start editing on the next line

    O

    start editing on the previous line

    :wq or ZZ

    write file and exit

    ctrl-v

    visual block select (rectangular)

    shift-v

    visual line select

    ctrl(or shift)-v y or d

    copy or delete selected text

    yy

    yank (copy) current line

    yNNN arrow up/down

    yank NNN lines above or below

    p

    paste the yanked buffer

    cw

    change word (delete word under cursor and go into edit mode)

    cNw

    change N words

    e!

    		reload the file (revert)
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