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Shell: using sed in backticks

I want to avoid special characters inside a string automatically. I thought about repeating this chain and blowing it through some seeds. It doesn't seem to work inside backticks. So why

echo "foo[bar]" | sed 's/\[/\\[/g'

return

foo\[bar]

but

FOO=`echo "foo[bar]" | sed 's/\[/\\[/g'` && echo $FOO

just returns

foo[bar]

?

Unlike sed, tr works great inside backticks:

FOO=`echo "foo[bar]" | tr '[' '-' ` && echo $FOO

returns

foo-bar]
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3 answers


You need to avoid backslashes between backslashes.

FOO=`echo "foo[bar]" | sed 's/\\[/\\\\[/g'` && echo $FOO


Alternatively use $()

(this is really the recommended method).

FOO=$(echo "foo[bar]" | sed 's/\[/\\[/g') && echo $FOO
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How can I not use backlinks but use $ ()?

FOO=$(echo "foo[bar]" | sed 's/\[/\\[/g') && echo $FOO


if you insist on using reverse steps i think you need to additionally rip out all \ into double \

FOO=`echo "foo[bar]" | sed 's/\\[/\\\\[/g'` && echo $FOO
+15


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This is usually a case of underexposure

FOO=`echo "foo[bar]" | sed 's/\[/\\\[/g'` && echo $FOO
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