Is there a way to get a program I can run via the command line that would do a checksum of a remote file? For instance get a checksum of https://stackoverflow.com/opensearch.xml
I want to be able get an update of when a new rss/xml entry is available. I was thinking I could do a checksum of a file every once in a while and if it is different then there must be an update. I'm looking to write a shell script that checks new rss/xml data.
A quick way to do this with curl is to pipe the output to sha1sum as follows:
curl -s http://stackoverflow.com/opensearch.xml|sha1sum
In order to make a checksum on the file, you'll have to download it first.
Instead of this, use If-Modified-Since in your request headers, and server will respond with 304 not modified header and without content, if the file is not changed, or with the content of the file, if it was changed. You may be interested also in checking for ETag support on the server.
If downloading the file is not a problem, you can use md5_file to get md5 checksum of the file
curl
curl has an '-z' option:
-z/--time-cond <date expression>|<file>
(HTTP/FTP) Request a file that has been modified later
than the given time and date, or one that has been modified before
that time. The <date expression> can be all sorts of date strings
or if it doesn't match any internal ones, it is taken as a filename
and tries to get the modification date (mtime) from <file> instead.
See the curl_getdate(3) man pages for date expression details.
So what you can do is:
$ curl http://stackoverflow.com/opensearch.xml -z opensearch.xml -o opensearch.xml
This will do actual download if remote file is younger than the local one (local file may absent - in this case it will be downloaded). Which seems to be exactly what you need...
wget
wget also has an option to track timestamps - -N
When running Wget with -N, with or without -r or -p, the decision as to whether
or not to download a newer copy of a file depends on the local and remote
timestamp and size of the file.
-N, --timestamping Turn on time-stamping.
So in case wget one can use:
$ wget -N http://stackoverflow.com/opensearch.xml
You can try this under your bash:
wget <http://your file link>
md5sum <your file name>
You should first examine the HTTP headers to see if the server itself is willing to tell you when the file is from; it's considered bad form to fetch the entire file if you don't need to.
Otherwise, you'll need to use something like wget or curl to fetch the file, so I really hope you don't plan to be working with anything large.
Related
I am running a curl command that passes cookies.txt with an authentication string generated in a previous step and attempts to download a file that is generated daily. This works great when the file exists, but the problem i'm running into is when the file is not yet released. I start listening at 5PM and I re-run the script every 5 minutes and attempt to grab the file. Currently I check to see if the file size is above a certain value, but it doesn't work very well.
Is there any way to set curl to only create a file if the file it's attempting to grab exists? I'd really like to avoid the whole checking file size practice since that's really unreliable for multiple files of differing sizes.
Curl Command:
curl -b cookies.txt -J -L -v -O https://file_http_example.thespot.com/cleared_product_$(date +"%Y_%m_%d").xlsx
I try comparing the file size by doing the following:
fileSize=500
targetFileSize=$(wc -c file_name_$(date + "%Y_%m_%d").xlsx | awk '{print $1}')
if [ "$targetFileSize" -gt "$fileSize" ]
then keep the file otherwise delete it.
UPDATE:
I just ran the script with the below changes and I still saved a file. This is what's saved in the file:
Assuming the server respond with an HTTP error when the file isn't available, you can use curl's -f flag :
-f, --fail Fail silently (no output at all) on HTTP errors
This will avoid creating a file when the server responds with for an HTTP 404 or other error code.
I'm currently using wget to download specific files from a remote server. The files are updated every week, but always have the same file names. e.g new upload file1.jpg will replace local file1.jpg
This is how I am grabbing them, nothing fancy :
wget -N -P /path/to/local/folder/ http://xx.xxx.xxx.xxx/remote/files/file1.jpg
This downloads file1.jpg from the remote server if it is newer than the local version then overwrites the local one with the new one.
Trouble is, I'm doing this for over 100 files every week and have set up cron jobs to fire the 100 different download scripts at specific times.
Is there a way I can use a wildcard for the file name and have just one script that fires every 5 minutes for example?
Something like....
wget -N -P /path/to/local/folder/ http://xx.xxx.xxx.xxx/remote/files/*.jpg
Will that work? Will it check the local folder for all current file names, see what is new and then download and overwrite only the new ones? Also, is there any danger of it downloading partially uploaded files on the remote server?
I know that some kind of file sync script between servers would be a better option but they all look pretty complicated to set up.
Many thanks!
You can specify the files to be downloaded one by one in a text file, and then pass that file name using option -i or --input-file.
e.g. contents of list.txt:
http://xx.xxx.xxx.xxx/remote/files/file1.jpg
http://xx.xxx.xxx.xxx/remote/files/file2.jpg
http://xx.xxx.xxx.xxx/remote/files/file3.jpg
....
then
wget .... --input-file list.txt
Alternatively, If all your *.jpg files are linked from a particular HTML page, you can use recursive downloading, i.e. let wget follow links on your page to all linked resources. You might need to limit the "recursion level" and file types in order to prevent downloading too much. See wget --help for more info.
wget .... --recursive --level=1 --accept=jpg --no-parent http://.../your-index-page.html
This is what I'm trying to achieve :
User uploads file1.jpg to Server A
Using wget Server B only downloads file1.jpg from Server A if the file is newer than the one that already exists on Server B and then replaces the file on Server B with the new one.
I know I can use :
wget -N http://www.mywebsite.com/files/file1.jpg
To check that the target file is newer than the source but I'm a little confused as to how I format the command to let it know what and where the actual source file is?
Is it something like? :
wget -N http://www.mywebsite.com/files/file1.jpg /serverb/files/file1.jpg
Cheers!
You can use -P option to specify the directory where the file(s) will be downloaded:
$ wget -N -P /serverb/files/ http://www.mywebsite.com/files/file1.jpg
You are also talking about downloading and replacing the file. Be aware, that wget overwrites the file, so it is "broken" while being downloaded. I don't think you can do atomic replacement of the file using only wget. You need a small script that uses temporary files and move to atomically replace the file in Server B.
In wget I am trying to get the list of files and its properties from FTP server using below Wget command,
wget --no-remove-listing ftp://myftpserver/ftpdirectory/
This will generate two files: .listing (this is what I am looking in cURL) and index.html which is the html version of the listing file.
My expectation:
In cURL how to achieve this scenario?
What is the command to get the .listing and index.html file from FTP/SFTP server using CURL.
This is what I found on http://curl.haxx.se/docs/faq.html#How_do_I_get_an_FTP_directory_li
If you end the FTP URL you request with a slash, libcurl will provide you with a directory listing of that given directory. You can also set CURLOPT_CUSTOMREQUEST to alter what exact listing command libcurl would use to list the files.
The follow-up question that tend to follow the previous one, is how a program is supposed to parse the directory listing. How does it know what's a file and what's a dir and what's a symlink etc. The harsh reality is that FTP provides no such fine and easy-to-parse output. The output format FTP servers respond to LIST commands are entirely at the server's own liking and the NLST output doesn't reveal any types and in many cases don't even include all the directory entries. Also, both LIST and NLST tend to hide unix-style hidden files (those that start with a dot) by default so you need to do "LIST -a" or similar to see them.
Thanks & Regards,
Alok
I have checked it on WIN->CygWin and it works for me:
Do not forget to use / at the end of the path.
$ curl -s -l -u test1#test.com:Test_PASSWD --ftp-ssl 'ftps://ftp.test.com/Ent/'
I have an automatic backup of a file running on a cronjob. It outputs into a folder, let's call /backup, and appends a timestamp to each file, every hour, like so:
file_08_07_2013_01_00_00.txt, file_08_07_2013_02_00_00.txt, etc.
I want to download these to another server, to keep as a separate backup. I normally just use wget and download a specific file, but was wondering how I could automate this, ideally every hour it would download the most recent file.
What would I need to look into to set this up?
Thanks!
wget can handle that, just enable time-stamping. I'm not even going to attempt my own explanation, here's a direct quote from the manual:
The usage of time-stamping is simple. Say you would like to download a
file so that it keeps its date of modification.
wget -S http://www.gnu.ai.mit.edu/
A simple ls -l shows that the time stamp on the local file equals the state of the Last-Modified
header, as returned by the server. As you can see, the time-stamping
info is preserved locally, even without ‘-N’ (at least for http).
Several days later, you would like Wget to check if the remote file
has changed, and download it if it has.
wget -N http://www.gnu.ai.mit.edu/
Wget will ask the server for the last-modified date. If the local file has the same timestamp as
the server, or a newer one, the remote file will not be re-fetched.
However, if the remote file is more recent, Wget will proceed to fetch
it.