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I am failing to add comments for multi-line statements in bash script. Seems that bash is not interpreting.

Since comments can really be useful because there are potential 4-5 lines, can anyone advice me how to achieve this?

This is just basic example, which is - not working.

#!/bin/bash

iptables -A INPUT \
#Comment for rule bellow
-p tcp --dport 21 \
# Comment for rule bellow no2
-s 10.0.0.1 \
-j ACCEPT

I just give a plain example. Allowing comments can be more easier for complex examples (this is not complicated example, but you got a point) like this:

grep some_file \
#awk does that...
awk '{print $1}' \
#sed does that...
sed 's/match1/match2/g'

Of course there are no whitechars behind \.

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1 Answer 1

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2

A line broken into several lines by escaping the newline is still only one line.

A comment stretches from the # to the end of the line, no matter if that line is broken into many lines or not.

What the shell parses when you write

echo hello \
# world

is

echo hello # world

This is different though (and works):

grep hello |
# now sed:
sed 1p

Since each part of the pipeline is complete on its own line, it's possible to intermingle the lines with comments, as long as the newlines are not escaped.

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  • Yes, true, forgot to include | in second example. Thank you for explanation! Commented Mar 11, 2017 at 23:01

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