bash - search a letter in a string - awk

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Search a letter in a string using grep
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$ string="unix-bash 2389"

$ character="-"

$ echo $string | grep -q "$character" && echo "found" || echo "not found"
found

$ character="@"

$ echo $string | grep -q "$character" && echo "found" || echo "not found"
not found

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Search a letter in a string using awk
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$ character="@"

$ echo $string | awk -vc="$character" '{if(gsub(c,"")) print "Found";else print "Not Found"}'
Not Found

$ character="-"

$ echo $string | awk -vc="$character" '{if(gsub(c,"")) print "Found";else print "Not Found"}'
Found