Bash Scripting

 Bash Scriping:

Entire course: here

Types of shells in linux -> here

Use of she-bang -> here

echo and escape characters -> here

Array basics -> here and here

loops == for -> here while -> here

functions in bash -> here

IFS -> here

Grep -> here

Awk -> here loops in awqk -> here condtional statements-> here

grep vs sed vs awk -> here

shell parameter expansion -> here

printf -> here

AWK series by tecmint:

part1

part2

part3

part4

part5

part6

part7

part8

part9

part10

part11

part12

part13

all search techniques

Important points:

1.By default, read interprets the backslash as an escape character, which sometimes may cause unexpected behavior. To disable backslash escaping, invoke the command with the -r option.

Below is an example showing how read works when invoked with and without the -r option:

2.echo by itself displays a line of text. It will take any thing within the following "..." two quotation marks, literally, and just print out as it is. However with echo -e you're making echo to enable interpret backslash escapes. So with this in mind here are some examples

INPUT: echo "abc\n def \nghi" 

OUTPUT:abc\n def \nghi

INPUT: echo -e "abc\n def \nghi"

OUTPUT:abc

 def 

ghi

Note: \n is new line, ie a carriage return. If you want to know what other sequences are recognized by echo -e type in man echo to your terminal.

3.The only difference between @ and * is when the form ${my_array[x]} is surrounded with double-quotes. In this case, * expands to a single word where array elements are separated with space. @ expands each array element to a separate word.