DevChatt 2010 - *nix Cmd Line Kung Foo

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  • 1. *nix Command Line Kung Foo DevChatt, March 2010
  • 2. Who is this guy? Brian Dailey realm3 web applications Nashville
  • 3. Why the command line?
  • 4. It is concise.
  • 5. It is consistent.
  • 6. It saves time.
  • 7. What command line?
  • 8. Posix compliant shell (Preferably bash or dash.)
  • 9. Not using *nix? Pity. Mac OS X: You're good! Windows: Use cygwin (preferable) or a Unix port such as: http://unxutils.sourceforge.net/ Other: PuTTY + Amazon EC2, Ubuntu Live CD, etc.
  • 10. Basics: Keyboard Navigation
  • 11. Shell Keyboard Navigation Basics ↑↓ - Scroll through previous commands Ctrl+U - Clear all before cursor Ctrl+K - Clear all after cursor Ctrl+A - <Home> Ctrl+E - <End> Alt+B - Move cursor back one ”word” (Similar to Ctrl+ ← ) Alt+F - Move cursor forward one ”word” (Ctrl+ -> ) Alt+Bckspc - Delete previous ”word” (Also, Ctrl+W) Alt+. - Recall last command argument Tab - Autocomplete commands, files, folders, and more. Ctrl+L - Clear the screen Ctrl+_ - Undo CTRL+R - Recall previous commands Esc, T - Swap last two words These shortcuts are nearly universal (bash, MySQL) due to use of the GNU Readline library. Exhaustive list is available here: http://onlyubuntu.blogspot.com/2007/03/bash-shell-keyboard-shortcuts-for-linux.html
  • 12. Goodbye, Mouse! Example: mysql> SELECT user.id, user.username, user.email, user.address, user.city, user.state, user.name, userfile.file_name, userfile.metadata, userfile.other_stuff FOM user JOIN userfiles ON user.id = userfile.user_id AND user.id BETWEEN 1 AND 100 AND user.created BETWEEN '2008-10-10' AND '2009-10-10' AND user.is_active = 1 AND user.name LIKE 'Frodo%' LIMIT 10; [] n00b: Hold backspace key for 30 seconds. Fix, retype. Good: Press Alt+B to jump backwards one word at a time. Holy Hand Grenade: Press Alt+3,0,B to jump backwards 30 words.
  • 13. Shell Keyboard Navigation Kill and yank = Cut and paste Kill Commands: Ctrl+U - Kill all before cursor Ctrl+K - Kill all after cursor Alt+Bckspc – Kill previous word All kill commands place text into a buffer (aka “kill ring”). Ctrl+Y – Yank Alt+Y - Rotate kill ring, yank new top Technically yanks text from top of “kill ring”. To rotate through the ring you must first yank, then press Alt+M to rotate.
  • 14. Shell Keyboard Navigation Use Tab for auto-completion! $ svn ci -m”Fixed issue.” fil[tab] ↓ $ svn ci -m”Fixed issue.” filename.php [Tab][Tab] shows all available matches: $ svn ci -m”Fixed issue.” f[tab][tab] filename.php frodo_baggins.php friendly_fellow.php Enable programmable bash completion for further efficiency (compete args). $ git c[tab][tab] checkout cherry cherry-pick ci clean clone co commit config
  • 15. Shell Keyboard Navigation !! - Run the last command (same as ↑ +return) !my - Runs last cmd starting with ”my”, e.g., ” mysql -uroot -p db” !my:p - Find last cmd starting with ”my” and print it out vi !$ - Replaces !$ with last argument in previous command vi !* - Insert all arguments from previous command ^foo^bar - Run previous command but replace first “foo” with “bar” !!:gs/foo/bar – Run previous command, but replace all instances of “foo” with “bar” cd - - change to previous working directory A very useful (and more comprehensive) list is available here: http://mail.linux.ie/pipermail/ilug/2006-May/087799.html Also recommended: http://www.catonmat.net/blog/the-definitive-guide-to-bash-command-line-history/
  • 16. Shell Basics: I/O Redirect Concept can be thought of as ” pipes ” and ” streams ” Negates the need for an application to write to a file, only for another application to read it.
  • 17. I/O filters less – Interactive text pager with search capability. sort – Sort lines (alphabetically, numerically, etc) grep – Regular expression searches uniq – Detect (report or omit) repeated lines sed – Stream EDitor awk – powerful pattern scanning and text processing language xargs – build and execute commands from input cut - divide into columns There are a lot more of these tools!
  • 18. I/O Basic example of standard output: # format an XML file and feed it out to formatted.xml $ xmllint feed.xml --format > formatted.xml # same as above, but append to existing file. $ xmllint feed.xml --format >> formatted.xml Standard input: $ mysql -uuser -p db1 < schema.sql Or both: $ mysql -uuser -p db1 < schema.sql > log.txt Can also redirect stderr (errors). Use the pipe! $ history | grep svn
  • 19. I/O Examples of pipe chaining... Colorize Subversion diff output: $ svn diff | colordiff | less -R Search files for child classes, do not include test files, sort them alphabetically, and paginate. $ grep -r -n -H '^class.*extends.*{$' * | grep -v test | sort | more
  • 20. I/O Example: # copy the latest changeset to a git-less server $ git log -1 --name-status | # only get files added or modified grep '^[AM]s' | # strip out status from stream sed 's/^[AM]s*//' | # scp to server (one at a time), retaining path xargs -I {} scp {} [email_address] :dir/{} (Disclaimer: There are better ways to do deploy changes.)
  • 21. Holy smokes! How will I remember to type all that?
  • 22. Let's automate this stuff!
  • 23. Introducing Alias alias deploy=”git log -1 --name-status | grep '^[AM]s' | sed 's/^[AM]s*//' | xargs -I {} scp {} [email_address] :dir/{}” # Other Examples # List files in friendly format alias l='ls -l' # Colorize svn diff, use less -R to accept colors alias sdv='svn diff | colordiff | less -R' # Do not allow updates or deletes without a primary key alias mysql='mysql --i-am-a-dummy'
  • 24. Alias Things to know: With alias, all arguments are appended to the command. Save your aliases to your .bashrc to automatically use in new sessions.
  • 25. Alias # Usage: fun [name] alias fun='echo $1 is having fun!' $ fun Brian is having fun! Brian Alias is only useful as the beginning of a command. Arguments don't work well, can't do loops, etc.
  • 26. Shell Functions Look up PHP command arguments: phpargs() { # $1 is the first argument passed # get php page from manual mirror curl -s http://us3.php.net/$1 | # pull all text in target div sed -n '/<div class=&quot;methodsynopsis dc-description&quot;>/,/</div>/p' | # strip out HTML tags sed 's/<[^>]*>//g' | # strip out line feed tr -d &quot; &quot; # add ending line echo } Then from the command line: $ phpargs in_array bool in_array ( mixed $needle, array $haystack [, bool $strict ] ) The only way to learn scripts is to write them!
  • 27. Further Resources Comprehensive Introduction to the shell http://www.linuxcommand.org/learning_the_shell.php Bash keyboard shortcuts http://onlyubuntu.blogspot.com/2007/03/bash-shell-keyboard-shortcuts-for-linux.html Bash arguments http://www.deadman.org/bash.html Bash programmable completion: http://www.debian-administration.org/articles/316 http://freshmeat.net/projects/bashcompletion/ IBM Bash By Tutorial Series http://www.ibm.com/developerworks/library/l-bash.html http://www.ibm.com/developerworks/library/l-bash2.html http://www.ibm.com/developerworks/library/l-bash3.html Cat on Mat: http://catonmat.com/
  • 28. Thanks! Any questions? Brian Dailey realm3 web applications Web: http://realm3.com/ Twitter: @brian_dailey Email: brian@realm3.com/ Phone: 917-512-3594 slide-bg: http://bit.ly/xc0m1 Kudos to: http://asi9.net/