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up vote 4 down vote favorite

I've a string separated with commas where i want to find my input in that line

echo US | grep "US,CA,CH,JP"

The output is empty! How should i use grep to find my input in that string?

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up vote 11 down vote accepted

Swap the arguments of the commands:

echo "US,CA,CH,JP" | grep US

In:

echo US | grep "US,CA,CH,JP"

you are looking for the string (pattern) US,CA,CH,JP in the input string US, which is not matching expectedly.

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up vote 9 down vote

Unless you were expecting the commas to act like an "or" statement, in which case you just need to change the commas to pipes and use the -E option for Extended regular expressions:

echo US | grep -E "US|CA|CH|JP"

Or change the commas to newline characters:

echo US | grep "US
CA
CH
JP"
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up vote -1 down vote

I would use $echo US | grep -i "US|CA|JP|CH"

Instead of eco give it a list or something, where it can actually can go and look for patterns, instead of looking for them in "US"

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You forgot -E. – reinierpost 6 hours ago

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