Below is the shell script I am trying to find the meaning.
sed 's/19984 $/98400 /' | sed 's/19992 $/99200 /'
I expect 19984 $ will get replaced with 98400 and this string will be passed to next sed command which replace 19992 $ with 99200 .
But when I executed the script below with sample input
echo "19984 $ need to be replaced with 98400 "| sed 's/19984 $/98400 /' | sed 's/19992 $/99200 /'
I get the same string
"19984 $ need to be replaced with 98400"
I hope something I am missing here. Please help me. I am new to shell scripts. Thanks in advance!
For sed, $
is a reserved character to you have to escape it ( \\$
) to be parsed properly:
$ echo "19984 $ need to be replaced with 98400 "| sed 's/19984 \$/98400 /'
98400 need to be replaced with 98400
All together:
$ echo "19984 $ need to be replaced with 98400 "| sed 's/19984 \$/98400 /' | sed 's/19992 \$/99200 /'
98400 need to be replaced with 98400
So you need to keep it like it is.
$
can mean a lot of things:
- a normal character.
- end of line.
- name of a variable.
The way you got the code it means the second case: end of line:
$ echo "19984 " | sed 's/19984 $/98400 /'
98400
$ echo "19984 something" | sed 's/19984 $/98400 /'
19984 something
so sed will match just the cases in which the line ends with 19984
. Otherwise it won't match.
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