Ruby regex - escape all

Question

I have this string:

string_to_replace = 'if [ "${USER_CONFIG}" != "" ] ; then'

I want to get:

'Sample Only!!!!!'

I am doing:

string_to_replace.sub(/if [ "${USER_CONFIG}" != "" ] ; then/, 'Sample Only!!!!!')

But I do not get the desired result.

Is there a way to escape all regex characters at once in this string?

There is no point in using a regex if you replace literal strings. Regular expressions are good to use when the string you need to match is not known beforehand, but that follows some pattern that can be defined with regex. — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Jan 4, 2017 at 8:53

Meninx - メネンックス · Accepted Answer · 2017-01-04 22:59:52Z

2

Change this :

/if [ "${USER_CONFIG}" != "" ] ; then/

To this:

'if [ "${USER_CONFIG}" != "" ] ; then'

or
string_to_replace

or
/if \[ "\${USER_CONFIG}" != "" \] ; then/

or
"if \[ \"\${USER_CONFIG}\" != \"\" \] ; then"

in sub() function.

edited Jan 4, 2017 at 22:59

answered Jan 4, 2017 at 8:43

Meninx - メネンックス

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5 Comments

Mark Estrada Over a year ago

thanks mate, that worked! Just would like to ask though why does it work? I would like to know if you know the reason why my first code doesn't work if you may. I am beginning ruby and I would like to expand my understanding on this topic.

Meninx - メネンックス Over a year ago

[ ] and $ are special characters you need to escape them to get their literals. if you try /if \[ "\${USER_CONFIG}" != "" \] ; then/ this pattern will work.

sawa Over a year ago

Your 1, 2, and 4 all give a string, which is not what the OP was asking for. And your 3 gives what the OP was asking for, in a way that OP was most likely trying to avoid (OP wanted to do it "all at once"). Hence, it is not an answer to the question at all. However, this indirectly suggests what OP should have been doing.

Meninx - メネンックス Over a year ago

@sawa don't be hypermetropic. Try to "see the trees for the forest !". If you find it is not a good answer for the question you can write another answer which include some functions for direct escaping.

sawa Over a year ago

@Meninx-メネンックス Here you go.

sawa · Accepted Answer · 2017-01-04 11:36:16Z

0

The real answer to the question as is is, yes, there is. And the way to do it is:

Regexp.new(Regexp.escape(string_to_replace))
#=> /if\ \[\ "\$\{USER_CONFIG\}"\ !=\ ""\ \]\ ;\ then/

edited Jan 4, 2017 at 11:36

answered Jan 4, 2017 at 11:30

sawa

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