Main Page

Welcome to the PaskvilWiki!

The future shape of this wiki is unknown for now, let's hope it'll be something good...

This is partially a private wiki - viewing is allowed to all, but editing is allowed only to registered users.

This is more of a prevention than denial - I don't have time to monitor and moderate edits; - you're more than welcome to request registration, all contributors are very much welcome!

Just write me at josef.at.paskvil.dot.com.

Short Notes - Tips and Tricks

4store

• setup and installation
• running 4store
• data import
• data import and querying from Python
• Turtle file printer (in Python)

Apache

• Note on serving of local files
• Self-Signed SSL Certificate
• Enable SSL/HTTPS in Apache
• .htaccess and mod_rewrite Tricks

Bash

• Extensions and File Name
• File Test Operators
• Commands and Shortcuts

$ sudo !!                         - run last command as root
$ !!:gs/foo/bar                   - run last command, replacing 'foo' with 'bar'
$ ^foo^bar                        - run last command, replacing 'foo' with 'bar'
$ cp filename{,.bak}              - create a .bak copy of file
<Ctrl-x> <Ctrl-e>                 - open $EDITOR to edit current command line; upon exit, content will be run
$ <space>command                  - run the command without saving it in history
$ > file.txt                      - empty a file
<Alt+.>                           - put last argument on cursor place; repeat to cycle through
$ (cd /tmp && ls)                 - jump to /tmp, execute ls, and jump back here
$ pushd /tmp .... $ popd          - goes to /tmp, remembering current location; at later time, popd will bring you back
$ \command                        - run command without using aliases
$ rm !(pattern|pattern)           - delete files that do not match given patterns
$ find . -mtime +5 -exec rm {} \; - delete all files in this folder that are older than 5 days
<Ctrl-u> ... <Ctrl-y>             - Ctrl+u will cut current command, then you can do whatever you need, and Ctrl+y will paste it back
$ date -d @1234567890             - convert unix timestamp to human-readable

• Informations

$ mount | column -t               - pretty-print mount table
$ cat /etc/issue                  - display distro name

• Small Tricks

$ echo $(printf '%q' "A\"B")      - prints escaped string (in this case, > A\"B <)
$ mount -t tmpfs tmpfs /mnt -o size=1024m      - mount temporary RAM partition (fast access, non-persistent!)
$ disown -a && exit               - exit the shell while keeping all running processes alive
$ ssh -t remote_host screen -r    - directly connect to a remote screen process
$ for I in $(mysql -e 'show databases' -s --skip-column-names); do mysqldump $I | gzip > "$I.sql.gz"; done
                                  - backup all databases into individual files
$ fuser -k filename               - kill process that is locking given file
$ readom dev=/dev/scd0 f=/path/to/image.iso    - create CD/DVD ISO image
$ mkdir -p a/deep/dir/tree        - create nested directories fast
$ mount file.iso /mnt/iso -o loop - mount ISO file as drive /mnt/iso (dir has to preexist)
$ sudo touch /forcefsck           - force a file system check on the next reboot
$ ls | while read f; do something with file "$f"; done   - iterate through files even if they contain space in name

• lsof

$ lsof -nPi                       - list network connections
$ netstat -tlnp                   - print all listening ports with PID's (run as root to see all process names)
$ lsof -c gnome-terminal          - list files opened by given command
$ lsof +D [folder]                - discover all open files in the [folder]
$ lsof -p [pid]                   - list files opened by given PID
$ lsof -i :8080                   - list programs that have port 8080 open ("who to kill" if you get "port already in use")

C/C++

• How to clean up after child thread
• Non-blocking IO using sockets
• Shared Libraries on Linux+GCC
• Singleton
• std::move Semantics
• Converting between std::string and std::wstring in C++11

ElasticSearch

• Installation
• What You Get
• Indexing, Routing, etc.
• Deleting
• Getting and Multi-Getting
• Updating
• Search and Query DSL

ffmpeg

• Rip DVD into FLV (or anything else)
• Video File with Still Image and Audio
• process all files, may include spaces in file name:

ls *.avi | while read f; do ffmpeg -i "$f" ...params... "$f.mkv"; done

• if you're having problems with input format, passing video through mpeg typically helps:

ffmpeg -i file.mkv -qscale 2 -f mpeg - | ffmpeg -i - ...params... file.avi

• downmix 5.1 dolby to normal stereo:

ffmpeg -i file.mkv ...params... -acodec libmp3lame -ar 44100 -ac 2 file.avi

Kyoto Cabinet and Kyoto Tycoon

• Setup and Install Kyoto Cabinet
• Setup and Install Kyoto Tycoon
• KT's RPC API Reference

Linux Administration

• Reset Compiz to Default Settings
• Enable and Start sendmail
• Installing sendmail
• Sending Emails using sendmail
• Find and Mark Bad Blocks

MAC OSX

• Asynchronous Execution
  • NSThread
  • performSelectorInBackground
  • dispatch_async
• MacPorts

$ sudo port selfupdate
$ sudo port upgrade outdated
$ sudo port uninstall inactive
$ (just once) sudo port install port_cutleaves
$ sudo port_cutleaves

MongoDB

• Installation on Ubuntu
• Troubleshooting on Desktop
• Use in PHP via PECL driver

MySQL

• Error 1045: Access denied
• The insert ... on duplicate key update Pitfall

PDF

• Merging PDF Files using GhostScript
• Cutting PDF Files using GhostScript
• Converting to PDF using GhostScript

PHP

• Convert Accented Characters to Non-Accented
• Upload a File using cURL
• HTTP Post in Pure PHP (without cURL)
• Prevent Client Disconnect from Killing PHP
• Disconnect Client and Continue Processing

Python

• Timing, and memory, on Linux

Security

• Password Generators
• SSH Access using pubkey's Authentication
• Using RSync together with SSH

Subversion/SVN

• Simple Guide to SVN Client
• Creating a SVN Repository|Creating SVN Repository
• Moving a SVN Repository
• Change Repository URL (Subversion 1.7+)
• Setup a SVN Server on a Shared Hosting with no root Access
• creating and applying patch (the --diff-cmd is necessary in case you set some graphical diff-viewer in ~/.subversion/config):

cd root_of_project
svn di --diff-cmd diff > ~/patch.diff
cd root_of_other_project
patch -p0 -i ~/patch.diff

ViM

• Delete all lines matching a pattern
• Directly type HTML entities
• Reformat a plain text paragraph

$ vim -x filename                      - open filename for editing, and save it encrypted (will prompt for a key)
:X                                     - set encryption for current file; use ':set key=' to disable encryption
                                       - put "set cm=blowfish" in your .vimrc to enable safer encryption by default
$ vim +10 [file] ; vim +/hello [file]  - open [file] at line 10, or at first occurrence of pattern 'hello' in file
:w !sudo tee %                         - save file via `sudo` (as root)

Web - HTML, CSS, JS, jQuery, etc.

• Multiple Submit Buttons and/or Multiple Forms on Page
• Make 'float' Elements Appear One under Another
• Upload a File via Form
• Override the IE's Problem with width
• Make an Element Fill In All the Remaining Space