I have a list of URLS that I need to check, to see if they still work or not. I would like to write a bash script that does that for me.
I only need the returned HTT
Use curl to fetch the HTTP-header only (not the whole file) and parse it:
$ curl -I --stderr /dev/null http://www.google.co.uk/index.html | head -1 | cut -d' ' -f2
200
Due to https://mywiki.wooledge.org/BashPitfalls#Non-atomic_writes_with_xargs_-P (output from parallel jobs in xargs
risks being mixed), I would use GNU Parallel instead of xargs
to parallelize:
cat url.lst |
parallel -P0 -q curl -o /dev/null --silent --head --write-out '%{url_effective}: %{http_code}\n' > outfile
In this particular case it may be safe to use xargs
because the output is so short, so the problem with using xargs
is rather that if someone later changes the code to do something bigger, it will no longer be safe. Or if someone reads this question and thinks he can replace curl
with something else, then that may also not be safe.
Curl has a specific option, --write-out
, for this:
$ curl -o /dev/null --silent --head --write-out '%{http_code}\n' <url>
200
-o /dev/null
throws away the usual output--silent
throws away the progress meter--head
makes a HEAD HTTP request, instead of GET--write-out '%{http_code}\n'
prints the required status codeTo wrap this up in a complete Bash script:
#!/bin/bash
while read LINE; do
curl -o /dev/null --silent --head --write-out "%{http_code} $LINE\n" "$LINE"
done < url-list.txt
(Eagle-eyed readers will notice that this uses one curl process per URL, which imposes fork and TCP connection penalties. It would be faster if multiple URLs were combined in a single curl, but there isn't space to write out the monsterous repetition of options that curl requires to do this.)
I found a tool "webchk” written in Python. Returns a status code for a list of urls. https://pypi.org/project/webchk/
Output looks like this:
▶ webchk -i ./dxieu.txt | grep '200'
http://salesforce-case-status.dxi.eu/login ... 200 OK (0.108)
https://support.dxi.eu/hc/en-gb ... 200 OK (0.389)
https://support.dxi.eu/hc/en-gb ... 200 OK (0.401)
Hope that helps!
wget -S -i *file*
will get you the headers from each url in a file.
Filter though grep
for the status code specifically.
This relies on widely available wget
, present almost everywhere, even on Alpine Linux.
wget --server-response --spider --quiet "${url}" 2>&1 | awk 'NR==1{print $2}'
The explanations are as follow :
--quiet
Turn off Wget's output.
Source - wget man pages
--spider
[ ... ] it will not download the pages, just check that they are there. [ ... ]
Source - wget man pages
--server-response
Print the headers sent by HTTP servers and responses sent by FTP servers.
Source - wget man pages
What they don't say about --server-response
is that those headers output are printed to standard error (sterr), thus the need to redirect to stdin.
The output sent to standard input, we can pipe it to awk
to extract the HTTP status code. That code is :
$2
) non-blank group of characters: {$2}
NR==1
And because we want to print it... {print $2}
.
wget --server-response --spider --quiet "${url}" 2>&1 | awk 'NR==1{print $2}'