Shell Programming and Scripting

we can use below sed command also

Code:

sed '/^[# The].*/d' $file

This means: delete any line that starts with #, space, T, h, or e ..
This means: delete any line that starts with ^, $, | or # ..

No. This grep looks for any line in file that starts with any character except for the characters $, |, ^, and #.

---------- Post updated at 00:37 ---------- Previous update was at 00:22 ----------

I don't understand why you have the |$ in these expressions.

If you want to remove lines starting with # and remove lines starting with The, you can do that with:

Code:

grep -Ev '^(#|The)'

The command:

Code:

grep -Ev '^(#|The|$)'

will remove any lines starting with #, lines starting with The, and empty lines.

---------- Post updated at 00:46 ---------- Previous update was at 00:37 ----------

The commands:

Code:

egrep -v '^(#|The|[$])'

and equivalently

Code:

grep -Ev '^(#|The|[$])'

will remove any line starting with #, any line starting with The, and any line starting with $.

I tried to translate it into what the net effect would be. It effectively deletes (does not print) lines that start with those characters / it prints lines that do not start with these characters.
edit: I agree there would be a difference in case of empty lines.

Code:

sed '/^[# The].*/d' $file

it delete the lines stared with # and The.

like

Code:

File is....
#srinivas
The book
To Scrutinizer

Here it delete first two lines only

---------- Post updated at 04:19 AM ---------- Previous update was at 04:14 AM ----------

can you give me an example

No it would leave only the first line

---------- Post updated at 04:19 AM ---------- Previous update was at 04:14 AM ----------

Code:

$ printf 'This\n\nis\n$a sample\n' 
This

is
$a sample

Code:

$ printf 'This\n\nis\n$a sample\n' | grep '^[^$|^#]'
This
is

vs.

Code:

$ printf 'This\n\nis\n$a sample\n' | grep -v '^[$|^#]'
This

is