dos2unix On Every File in a Dir

I am by no means a Linux expert and I find myself forgetting obvious commands if I haven't used them for a while.

Today, I found myself needing to apply the app 'dos2unix' on a bunch of files recursively in a directory.

After fumbling for a few minutes, this is what I came up with:

    find . -type f -exec dos2unix '{}' \;

Now hopefully, I wont forget again!

Enabling the Home/End/Delete Keys on a *nix Machine

Make the Home/End/Delete key function like you would assume that they would!

In your .profile file (create it if necessary in your home directory), if you add the following to the bottom (or top), you can enable the Home/End/Delete keys:

case $TERM in
xterm*)
      bind '"\e[1~": beginning-of-line'
      bind '"\e[3~": delete-char'
      bind '"\e[4~": end-of-line'
      bind '"\177": backward-delete-char'
      ;;
esac

This would enable the hot keys for your profile.

If you want to set them up system wide, then (as root) add the following to the end of your /etc/inputrc file:

"\e[1~": beginning-of-line
"\e[4~": end-of-line
"\e[3~": delete-char
"\177": backward-delete-char

Greasemonkey & Auto Updating Userscripts With Subversion

Some time ago, I wanted to create a way of auto updating my Greasemonkey userscripts so that I wouldn't have to somehow manually notify everyone when an update occured.

My scripts are kept in a subversion repository with WebDav support. So one of the first things that I did was examine the HTTP headers of my web server when I made a subversion request from my browser:

Date Fri, 24 Aug 2007 16:00:53 GMT 
Server Apache/2.0.54 (Unix) DAV/2 SVN/1.2.0 mod_perl/1.999.22 Perl/v5.8.5 
Etag "1390//some_script.user.js" 
Accept-Ranges bytes 
Content-Length 638 
Keep-Alive timeout=15, max=99 
Connection Keep-Alive 
Content-Type text/html; charset=UTF-8

The one thing to notice is the line with the Etag text. It pretty much displays the subversion version of my script, 'some_script.user.js'. So if I could get this information when my script loads and compare it to any value that I have stored previously, then I can cause my script to update itself quite easily!

So I created a function called check4Update(options) that did just that. In addition to my function, I also used cookie management code that I slighltly modified from webreference.com (included below).

The function that I created has a json object called options with the following parameters:

• url - the subversion URL for your userscript


• scriptname - the name of your script [defaults to the domain that the script acts upon; this may not be desirable, so please set it!]


• delay - the number of page refreshes to wait before nagging the user again [ defaults to 7]





Items in bold are required and items in italics are optional

 
window.check4Update = function(options) {
 var options = options || {}; 
 if (!url) {
  // we need this at least ...
  return;
 }
 var url = options.url;
 var scriptname = options.scriptname || location.host + "_script";
 var delay = options.delay || 7;
 
 // cookie_name is the name of the cookie that we will set with the 
 // value of version
 var cookie_name = scriptname
 
 // the version of the script. Initially, this will be null.
 var version =  getCookie(cookie_name);
 
 // the name of the cookie that indicates when we should nag 
 // about upgrading in case the user didnt want to upgrade their script
 var upgrade_cookie = scriptname+ '_DELAY_UPGRADE'
 
 try {
  GM_xmlhttpRequest({ 
   // head command because we are only interested 
   // in the Headers and not the script!
   method: 'HEAD',
   url: url,
   headers: {
            'User-agent': 'Mozilla/4.0 (compatible) Greasemonkey '+scriptname+'/1.0'
   },
   onload: function(responseDetails) {
            if (responseDetails.status == 200 || responseDetails.status == 202) {
            var headers = (responseDetails.responseHeaders).split('\n');
            for (var i in headers) {
    
            // go through and look for 'Etag'
            if (headers[i].indexOf('Etag') != -1) {
             var s = headers[i];
             
             // create a regular expression to parse the version
             var regx = /^.*Etag: \"(\d+)\/\/.*\"$/;
             regx = regx.exec(s);
             
             // here s will be our version obtained from the svn repository
             s = regx[1]
             
             //  here version would be a previously set version or null
             // if this is the first time running the script
             if (version) {
                      // here we get the nag count
                      var count = getCookie(upgrade_cookie)
                    
                      // if the nag count exists and is greater than 0, then decrement it
                      // and dont prompt to upgrade
                      if (count && count-- > 0) {
                      // user doesnt want to be notified
                     var now = new Date();
                     window.fixDate(now);
                     now.setTime(now.getTime() +  31*24*60*60*1000); // expire in a month
                     deleteCookie(upgrade_cookie);
                     setCookie(upgrade_cookie, count, now,"/", scriptname + ".com");
                     GM_log("Wont nag for " + count +" more reloads ....");
                     return;
                       }
                    
                    // so we have found a newer version of the script prompt to upgrade                    
                    if (s > version) { 
                      // ask the user if they wish to upgrade
                      // if they choose not to, then set a cookie to wait 'delay' page
                      // refreshes and then notify them to upgrade again
                      if (confirm("A newer version of this script exists!\n\tRemote Version: " +s+"\n\tYour Version: "+version+"\nWould you like to upgrade now?")) {
                     setCookie(upgrade_cookie, -1, null, "/", scriptname + ".com");
                     var now = new Date();
                     window.fixDate(now);
                     now.setTime(now.getTime() +  31*24*60*60*1000); // expire in a month
                     deleteCookie(cookie_name,"/", scriptname + ".com");
                     setCookie(cookie_name, s, now,"/", scriptname + ".com");
                     alert("Please reload the page once the script has been updated!")
                     // here we cause the page to refresh with the location of our script
                     // this will cause greasemonkey to prompt the user to install the script
                     location.replace(url)
                      } else {
                     // set a cookie to upgrade later
                     var now = new Date();
                     window.fixDate(now);
                     now.setTime(now.getTime() +  31*24*60*60*1000); // expire in a month
                     deleteCookie(upgrade_cookie,"/", scriptname + ".com");
                     setCookie(upgrade_cookie, delay, now,"/", scriptname + ".com");
                     GM_log("Won't notify of upgrades for a "+delay+" page refreshes!");
                      }
                    }
               } else {
                     // version wasnt previously set so we set the version in the cookie to
                     // be the current version of the script in svn repository
                     var now = new Date();
                     window.fixDate(now);
                     now.setTime(now.getTime() +  31*24*60*60*1000); // expire in a month
                     deleteCookie(cookie_name,"/", scriptname + ".com");
                     setCookie(cookie_name, s, now,"/", scriptname + ".com");
               }
            }
           }          
          }
   }, 
   onerror: function(responseDetails) {
          console.log('GM_xmlhttpRequest error: %s', responseDetails.responseText)
   }, 
   onreadystatechange: function(responseDetails) {
 
   }
  });
 } catch (exception){
  console.log('Error occurred while updating the script %s . The error was: %s', scriptname, exception);
 }
 
}

The code above is commented to indicate the logic behind it. If you need more information, please add a comment and I will explain any discrepancies. Also, if you can think of a better way of doing things, please let me know!

Below are the cookie management functions:

window.setCookie = function (name, value, expires, path, domain, secure) {
  var curCookie = name + "=" + escape(value) +
      ((expires) ? "; expires=" + expires.toGMTString() : "") +
      ((path) ? "; path=" + path : "") +
      ((domain) ? "; domain=" + domain : "") +
      ((secure) ? "; secure" : "");
   
  document.cookie = curCookie;
}


window.getCookie = function (name) {
  var dc = document.cookie;
  var prefix = name + "=";
  var begin = dc.indexOf("; " + prefix);
  if (begin == -1) {
    begin = dc.indexOf(prefix);
    if (begin != 0) return null;
  } else
    begin += 2;
  var end = document.cookie.indexOf(";", begin);
  if (end == -1)
    end = dc.length;
 
  return unescape(dc.substring(begin + prefix.length, end));
}


window.deleteCookie = function (name, path, domain) {
  if (getCookie(name)) {
    document.cookie = name + "=" +
    ((path) ? "; path=" + path : "") +
    ((domain) ? "; domain=" + domain : "") +
    "; expires=Thu, 01-Jan-70 00:00:01 GMT";
  }
}


window.fixDate = function (date) {
  var base = new Date(0);
  var skew = base.getTime();
  if (skew > 0)
    date.setTime(date.getTime() - skew); 
}

This is how one could call the this function from within their userscript.

window.check4Update({'url':'http://someurl.com/my_script.user.js', 'scriptname':'my_script_name', 'delay':7});

Finally, all of the code mentioned above was placed in my Greasemonkey userscript at the end of the onload event handler:

window.addEventListener('load',
  function () {
//... your user script code here ... //

// ... the auto update code here ... //
 }
,true);

Good luck!