New Lines in Echo

happymsg='Files Delivered\nFile1.txt\nFile2.txt\n'

echo $happymsg

Files Delivered\nFile1.txt\nFile2.txt\n'

echo -e $happymsg

Files Delivered

File1.txt

File2.txt

Unix Control Key Commands

ctrl-s - freeze scrolling screen

ctrl-q - unfreeze the screen, display continues

ctrl-c - interrupt a running program

ctrl-\ - same as ctrl-c but stronger when terminal doesn't respond

ctrl-z - suspends a running program

ctrl-h - deletes last char typed

ctrl-w - delete last word typed

ctrl-u - deletes last line typed

ctrl-r - redraws last line typed

ctrl-d - ends text for many Unix programs

Unix IF

File not exist

if [ ! -f filename ]

then

echo file does not exit

fi

Test variable

a=1

if [ $a == 1 ]

then

echo true

else

echo false

fi

vi cursor movement

Type:
  
To Move To:
 
  
 
h
  
one space to the left (also try left arrow)
 
  
 
j
  
one line down (also try down arrow)
 
  
 
k
  
one line up (also try up arrow)
 
  
 
l
  
one space to the right (also try right arrow)
 
  
 
$
  
end of current line
 
  
 
^
  
beginning of current line
 
  
 
Enter
  
beginning first word on the next line
 
  
 
G
  
end of file
 
  
 
:n
  
line n; use :0 to move the beginning of the file 
 
  
 
w
  
beginning of next word; 5w moves to the beginning of the 5th word to the right 
 
  
 
e
  
end of next word
 
  
 
b
  
beginning of previous word
 
  
 
Ctrl-b
  
one page up
 
  
 
Ctrl-f
  
one page down
 
  
 
%
  
the matching (, ), [, ], {, or }  
(Press % with your cursor on one of these characters to move your cursor its mate.)
 
 
 

SSH escape sequences

~. - terminate connection
~B - send a BREAK to the remote system
~C - open a command line
~R - request rekey (SSH protocol 2 only)
~^Z - suspend ssh
~# - list forwarded connections
~& - background ssh (when waiting for connections to terminate)
~? - this message
~~ - send the escape character by typing it twice

Note that escapes are only recognized immediately after newline

Unix substring

${#string} - Length of String

${string:position} - extract substring from $string at $position

-- position argument starts at 0, not 1.

${string/substring/replacement} - replace first match of $substring with $replacement

${string//substring/replacement} - replace all matches of $substring with $replacement
${string/#substring/replacement} - If $substring matches front end of $string, substitute $replacement for $substring
${string/%substring/replacement} - If $substring matches back end of $string, substitute $replacement for $substring

${string#substring} - Strip shortest match of $substring from front of $string

${string##substring} - Strip longest match of $substring from front of $string

${string%substring} - Strip shortest match of $substring from back of $string

${string%%substring} - Strip longest match of $substring from back of string

EXAMPLES
file=jack_of_all_trades
echo ${#file}
18

echo ${file:12}

trades

echo ${file:5:2}

of

echo ${file/of/OF}

jack_OF_all_trades

echo ${file//a/A}

jAck_of_All_trAdes

echo ${file:0:4}
jack

echo ${file/#j/A}

Aack_of_all_trades

echo ${file/%s/A}

jack_of_all_tradeA

file=aaa_bbb_ccc_aaa

echo ${file#aaa}

_bbb_ccc_aaa

echo ${file%aaa}

aaa_bbb_ccc_

Job commands

ps : report processes and pid numbers
jobs : current jobs and job id numbers
ctrl-S : stop screen scrolling
ctrl-Q : resume screen scrolling
ctrl-Z : suspend a job
stop %n : suspend background job n

bg : push the job to background
fg : bring a job to foreground
fg % job-id : foreground by job-id

ctrl-C : kill foreground process
kill -KILL pid#
kill -KILL %job-id


If job is running in foreground hit ctrl-z to suspend, then bg %n to run in background.