管道卷曲输出到grep

Question

Just a little disclaimer, I am not very familiar with programming so please excuse me if I'm using any terms incorrectly/in a confusing way.

I want to be able to extract specific information from a webpage and tried doing this by piping the output of a curl function into grep. Oh and this is in cygwin if that matters.

When just typing in

$ curl www.ncbi.nlm.nih.gov/gene/823951

The terminal prints the whole webpage in what I believe to be html. From here I thought I could just pipe this output into a grep function with whatever search term want with:

  $ curl www.ncbi.nlm.nih.gov/gene/823951 | grep "Gene Symbol"

But instead of printing the webpage at all, the terminal gives me:

 % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  142k    0  142k    0     0  41857      0 --:--:--  0:00:03 --:--:-- 42083

Can anyone explain why it does this/how I can search for specific lines of text in a webpage? I eventually want to compile information like gene names, types, and descriptions into a database, so I was hoping to export the results from the grep function into a text file after that.

Any help is extremely appreciated, thanks in advance!

Answer 1

Curl detects that it is not outputting to a terminal, and shows you the Progress Meter. You can suppress the progress meter with -s.

The HTML data is indeed being sent to grep. However that page does not contain the text "Gene Symbol". Grep is case-sensitive (unless invoked with -i) and you are looking for "Gene symbol".

$ curl -s www.ncbi.nlm.nih.gov/gene/823951 | grep "Gene symbol"
    <dt class="noline"> Gene symbol </dt>

You probably also want the next line of HTML, which you can make grep output with the -A option:

$ curl -s www.ncbi.nlm.nih.gov/gene/823951 | grep -A1 "Gene symbol"
    <dt class="noline"> Gene symbol </dt>
    <dd class="noline">AT3G47960</dd>

See man curl and man grep for more information about these and other options.