Tech in T: depth + breadth‎ > ‎OS‎ > ‎Linux‎ > ‎


variables should be sticking to =
WC=$(wc -l /home/scidb/temp/csvlist.dat  | cut -d" " -f1 )
echo $WC 

There are several ways to tell Bash to treat numbers as integers instead of strings, and to do basic arithmetic operations on them.  The first is to use the let command:
In addition to the let command, one may use the (( )) syntax to enforce an arithmetic context. If there is a $ (dollar sign) before the parentheses, then a substitution is performed (more on this below). White space is allowed inside (( )) with much greater leniency than with normal assignments, and variables inside (( )) don't require $ (because string literals aren't allowed).

let WC=$(sudo wc -l $MAIN_FILE  | cut -d" " -f1 )                                                                
((WC=$WC - 1 ))                                                                                                  
echo $WC         

comment    #

$ ls # kjenvdlkvndlkvnldk ndlkvn dlk vndlkvdlkdlldk anything after # is comment
echo Hello World

Bash Keyboard shortcuts

Ctrl + A: Go to the beginning of the line you are currently typing on
Ctrl + E: Go to the end of the line you are currently typing on

Ctrl + F: Forward one character.

Ctrl + B: Backward one character.

Meta + F: Move cursor forward one word on the current line

Meta + B: Move cursor backward one word on the current line

Ctrl + P: Previous command entered in history

Ctrl + N: Next command entered in history

Ctrl + L: Clears the screen, similar to the clear command

Ctrl + U: Clears the line before the cursor position. If you are at the end of the line, clears the entire line.

Ctrl + H: Same as backspace

Ctrl + R: Lets you search through previously used commands

Ctrl + C: Kill whatever you are running

Ctrl + D: Exit the current shell

Ctrl + Z: Puts whatever you are running into a suspended background process. fg restores it.

Ctrl + W: Delete the word before the cursor

Ctrl + K: Kill the line after the cursor

Ctrl + Y: Yank from the kill ring


$ echo `hostname` | sed 's/ip/foo/g'