在bash脚本中使用正则表达式

Question

I'm new to bash scripting, but I want to do the following:

I want to detect the pattern STRING_1 "STRING_2" in FILE_1 and append STRING_2 to FILE_2

what's a concise way to do this?

Answer 1

Your question is fairly vague; but my guess at what you wanted

if STRING_1 exists in FILE_1, append STRING_2 to FILE_2

answer=`grep -c STRING_1 FILE_1`
if [ "$answer" -gt 0 ] 
then
     echo "$STRING_2" >> FILE_2
fi

Answer 2

You could do something like:

   sed 's/STRING_1 \"(.*)\"/\1/g' FILE_1 >FILE_2

What's happening here, is sed is searing for everything between the first and second '/' from FILE_1 and sending what's between the second and third '/' to FILE_2.

() groups are assigned to \\1, \\2, etc... so everything in between the \\"s are your STRING_2.

Answer 3

grep -Po '(?<=aaa ")([^"]*)(?=")' FILE_1 >> FILE_2

Answer 4

If I understood correctly the question, and so you have a file containing:

word1a "word1b"
word2a "word2b"
word3a "word3b"

You can use sed to extract the value contained between quotes, and then redirect to a file

sed 's/.*"\(.*\)"/\1/' FILE_1 > FILE_2

Answer 5

You could also use this :

grep '^\s*STRING_1\s*\".*\"\s*$' FILE_1 | awk -F \" '{printf $2"\n"}' >> FILE_2

It correctly handles multiple blank characters of the input file, and appends a newline after STRING_2 at the end of FILE_2.

Answer 6

This is what I have right now:

sed 's/STRING_1\\s*:\\s*"([^"]*)"/\\1/g' "FILE_1" >> FILE_2;

I want it to detect the following pattern in file 1:

STRING_1   :   "STRING_2"

and save STRING_2 to file 2

but this doesn't work, it appends a lot of random stuff to FILE_2(that are not supposed to match)