Contents

Utils

sed -i 's/GBP/INR/g' .html //replace all instances of "GBP" in all .html files to "INR" sed -i 's~dir/file~dir/dir/file~g' // can use any delimiter (~ in this case) to find/replace text with "/" in it

cat order. | sort | grep Patterns //// concatenates all files starting with order., sorts and looks for the word Pattern 8:22:19 111, 1, Patterns of Enterprise Architecture, Kindle edition, 39.99 8:24:19 113, -1, Patterns of Enterprise Architecture, Kindle edition, 39.99 cat order. | sort | grep Patterns | cut -d"," -f2,5 ///// as above + splits/cuts using delimiter "," and keeps 2nd and 5th entries 1, 39.99 -1, 39.99

cat regex_practice | sed s/"[0-9\:] ([0-9])\, (.*)"/"\2, '\1'"/ //// sed / regexp / replacement / Note the indexes on 'replacement'. Reqd. regexp needs to be surrounded by ( ... ) to be included in the index count

cat regex_practice | grep "Kindle|Hardcover" | cut -d"," -f3 | sort | uniq -c ////// counts the instances of

tail -f orderbook.log //// automatically less orderbook.log //// can use / for forward search and ? for backward search when in 'less' find /home/sridhar -name "filename*" find /tmp/folder/ -type d -name keys -exec cp /tmp/a.kool {}\; ///////// copy a.kool into all sub-directories (direct or not) of /tmp/folder/ called 'keys' find ./ -name build.xml -exec grep "search_string" {} \; ////// search for search_string in all files called build.xml under ./ find ./ -name build.xml -exec sed -i 's/old_string/new_string/g' {} \; //// replace with new string all strings found above

find ./ -name build.xml -exec sed -i 's|version1.5"/>|version1.5"/>-->|' {} \;
Couldn't escape backslashes in regexp so best option is to use sed because the arguments in sed s/old/new/ are plain strings w/o the need for surrounding single or double quotes or escaping special characters. So for instance even this is allowed:

find . -path './*/src/golang.gurusys.co.uk/vendor' -prune -o -type f -exec egrep 'SetAlarm' {} + //ignore directory tree vendor in find/grep

find /etc/rc -exec echo Arg: {} ';' // executes command separately for each argument find /etc/rc -exec echo Arg: {} '+' // executes least possible arguments

cat build.xml | sed 's|version1.5"/>|version1.5"/>-->|'

Markdown

bold: text italics: * text * links: • inline: Google • ref-style [Google][1] [1]: http://www.google.com • readable [Google][google] [google]: http://google.com lists: -/+/*

new line: two spaces at end to force new line strikethrough: text

Vim

basics

vim

vim file_name
vim -O file1 file2 file3 // open files in vertically split windows
vim -o file1 file2 file3 // open files in horizontally split windows
i to insert
esc to stop insert
w/b to move forward/back by a word 
G$ to move to end of file
gg to move to start of file
:e! to refresh file from buffer
:set list // view end of line characters
x to delete
:x to exit/save
dd // delete line
d$ // delete until end of line
:<command> // : used if in vim, not reqd. if using .vimrc
:tabe <filename> : opens file in new tab  
:tabn : next tab  
:tabp : previous tab  
:tabnew : open new unnamed tab
:tabo : close all other tabs
:set syn=scala : sets syntax to scala - needs scala.vim in ~/.vim/syntax
:set spell spelllang=en_gb
:set shellcmdflag=-ic
nmap <C-n> :tabn<CR> //set in ~/.vimrc
nmap <C-p> :tabp<CR> //set in ~/.vimrc
:syntax on           //set in ~/.vimrc
:r <filename> //inserts contents of file below cursor
:r! <command> //inserts results of command below cursor
:% !<cmd>  // passes current buffer through command
:% !goimports // adds required imports to a go src file
:% s/keyword/new_keyword/g //find all instances of keyword and replace with new_keyword
* // find next occurrence of word under cursor
100>> //to indent 100 lines
5k // move 5 lines up 
5j // move 5 lines down
set shiftwidth=2 //in ~/.vimrc
au BufNewFile *.go 0r ~/.vim/go.skel | let IndentStyle = "go"
:vnew // new vertically split file
:vnew | r! <command> // output of command in new vertically split file
:w <newfilename> // writes to newfilename but continues with <oldfile>
:wa //saves all open tabs
:qa //closes all open tabs
:sav <newfilename> //writes to newfilename, closes <oldfile> and opens <newfile>
:w !sudo tee % // saves file if opened without root access
:grep -r xyz ./ | vim - //pipes results of grep into new file in vim

//Different tab setting for different files types. 8 for .go, 4 for .java

au FileType java setl sw=4 sts=4 et
au FileType go setl sw=8 sts=8 et

macros

Macros get recorded to registers

qa  // starts recording macro into register named 'a'
q   // stops recording
@a  // repeats macro actions recorded
"a  // access content of macro - can paste it using "ap
^   // goes to end of line - useful while recording macro
$   // goes to start of line - useful while recording macro

Can save macro in .vimrc

let @r = '8k8yy7jp' // apply macro using @r

registers

:reg // list registers
:reg a b c // filter registers to view
"0 // latest yanked text
"9 // oldest yanked text

So to paste the 5th oldest yanked text type "5p or in insert mode <Ctrl-r>5

4 read-only registers

". // last inserted text
"% // current file path 
": // most recent executed command. can repeat last command using @:
"# // confusing - maybe last edited file
"= // expression register

Ctrl-r (in insert mode) followed by any of the registers will paste register value:
Ctrl-r = // activates cmdline with '=' can do arithmetic operaion  like 3*5 will paste 15

Need vim-gtk to use * and + registers:

sudo apt-get install vim-gtk
"+y  // yanks visual mode selection into clipboard which can be pasted using Ctrl-V outside vim
:%y + // yanks entire buffer into clipboard which can be pasted using Ctrl-V outside vim

windows

vim -o file1.go file2.go // opens files in windows
:vs file2.go // open file2.go in new vertically split window
:sp file2.go // open file2.go in new horizontally split window
Ctrl-WW // toggles between windows
Ctrl-W +|> // increases height|width of current window
Ctrl-W -|< // decreases height|width of current window
v // Visual mode where arrow keys can be used to select text y //yanks selection in visual mode {Visual} "xy // In Visual mode "xy yanks selected text into register x to be pasted later in normal mode vep // pastes whatever is in buffer to replace word under cursor zc // folds zo // unfolds u //undo Cntl R //redo N gg // go to line N N k // go up N lines N j // go down N lines

diff -y --suppress-common-lines <(head -500 file2) <(head -500 file2)

operations

gUw //word to upper case guw //word to lower case ~ //toggle case of character under cursor % // when used on an open parenthesis/brace jumps to the corresponding close :digraph k μ=m ω=w Ω=W* ±=+-

emacs

    C-h C-h : help
    C-g : quit
    C-x b : switch buffers
    C-x right : right-cycle through buffers
    C-x left : left-cycle through buffers

    C-x k : kill buffer

    C-x 0 : close the active window
    C-x 1 : close all windows except the active window
    C-x 2 : split the active window vertically into two horizontal windows
    C-x 3 : split the active window horizontally into two vertical windows

    C-x o : change active window to next window

    C-x C-f : open file
    C-x C-s : save file

    C-x C-w : save file as

    C-space : set region mark
    C-w : kill region
    C-k : kill region between point and end of current line
    M-w : kill region without deleting
    C-y : yank region from kill ring
    M-y : move to previous item in the kill ring

    M-Y : move to next item in the kill ring

    C-_ : undo
    C-s : search forwards
    C-r : search backwards
    M-% : query replace (‘space’ to replace, ‘n’ to skip, ‘!’ to replace all)

    M-q : wrap text

    C-left : move one word left
    C-right : move one word right
    C-up : move one paragraph up
    C-down : move one paragraph down
    home : move to the beginning of the line
    end : move to the end of the line
    page up : move up a page
    page down : move down a page
    M- : move to end of buffer

tmux

Split screen vertically: Ctrlb and Shift5 Split screen horizontally: Ctrlb and Shift" Toggle between panes: Ctrlb and o Close current pane: Ctrlb and x

You can achieve more complex layouts by splitting panes. You can also have multiple windows with panes and switch between them.

Create windows: Ctrl-b and c Switch to next window: Ctrl-b and n Switch to previous window: Ctrl-b and p Destroy current window: Ctrl-b and Shift7 // or exit

Remap prefix from 'C-b' to 'C-a'

unbind C-b
set-option -g prefix C-a
bind-key C-a send-prefix

Split panes using | and -

bind | split-window -h
bind - split-window -v
unbind '"'
unbind %

Copy/paste

C-a [   // start
C-space // move to end
Alt-w   // copy into buffer
C-a ]   // paste works in vim visual mode as well

tmux rename-window doofus
C-a, rename-window

Misc

gedit syntax highlighting: /usr/share/gtksourceview-2.0/language-specs/scala.lang