I just  git on CentOS 6.8. When I run the command git from a bash-shell, I get the following error message:  -bash: /usr/bin/git: Bestand of map bestaat niet   Sorry, Dutch installation. Meaning: "File or folder doesn't exist". Git is installed.  When I run /usr/local/bin/git --version, I get the following output:  /usr/local/bin/git: /usr/local/lib/libz.so.1: no version information available (required by /usr/local/bin/git) git version 2.5.3   (not sure if the libz message is a problem).  which git points to /usr/local/bin/git, so that's fine too. echo $PATH returns /usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin. I've looked for aliases and other clues in .bash_profile, .bashrc and /etc/bashrc, but nothing...  How can I run git with just entering the command git?
When I execute a program without specifying the full path to the executable, and Bash must search the directories in $PATH to find the binary, it seems that Bash remembers the path in some sort of cache. For example, I installed a build of Subversion from source to /usr/local, then typed svnsync help at the Bash prompt. Bash located the binary /usr/local/bin/svnsync for "svnsync" and executed it. Then when I deleted the installation of Subversion in /usr/local and re-ran svnsync help, Bash responds:  bash: /usr/local/bin/svnsync: No such file or directory   But, when I start a new instance of Bash, it finds and executes /usr/bin/svnsync.  How do I clear the cache of paths to executables?
How does password salt help against a rainbow table attack? I'm having some trouble understanding the purpose of a salt to a password.  It's my understanding that the primary use is to hamper a rainbow table attack.  However, the methods I've seen to implement this don't seem to really make the problem harder.  I've seen many tutorials suggesting that the salt be used as the following:  $hash =  md5($salt.$password)   The reasoning being that the hash now maps not to the original password, but a combination of the password and the salt.  But say $salt=foo and $password=bar and $hash=3858f62230ac3c915f300c664312c63f.  Now somebody with a rainbow table could reverse the hash and come up with the input "foobar".  They could then try all combinations of passwords (f, fo, foo, ... oobar, obar, bar, ar, ar).  It might take a few more milliseconds to get the password, but not much else.  The other use I've seen is on my linux system.  In the /etc/shadow the hashed passwords are actually stored with the salt.  For example, a salt of "foo" and password of "bar" would hash to this: $1$foo$te5SBM.7C25fFDu6bIRbX1.  If a hacker somehow were able to get his hands on this file, I don't see what purpose the salt serves, since the reverse hash of te5SBM.7C25fFDu6bIRbX is known to contain "foo".  Thanks for any light anybody can shed on this.  EDIT:  Thanks for the help.  To summarize what I understand, the salt makes the hashed password more complex, thus making it much less likely to exist in a precomputed rainbow table.  What I misunderstood before was that I was assuming a rainbow table existed for ALL hashes. Having changed the scene units and unit scale, how can I change the default size of new objects? I am using blender most of the time to model things for my 3d printer. So a default unit in "meters" is not really helpful!  Within the scene settings it is simply possible to set the units to millimeter and the unit scael to 0.001 so everything seems to work as I want it to work...   But if I add a new primitive it uses its old default sizes in meters... so a new cube get's 2000 x 2000 millimeters instead of 2x2 or whatever will be useful..  Same for all other new objects...  How can I change the default sizes of new objects permanently?   And how can I change the settings in the application templates? Right now using ctrl+u changes the "general" template - perhaps because I loaded it before...   Thanks a lot and best regards Stefan Compact operators on an infinite dimensional Banach space cannot be surjective Polynomials with integer coefficients such that $p(a)=b,p(b)=c,p(c)=a$ While studying polynomials a question struck in my mind that  To have a polynomial $p(x)$ with integer coefficients and $a,b,c$ are three distinct integers, then is it possible to have $$p(a)=b$$$$p(b)=c$$$$p(c)=a$$ Commandline shortcut for current directory similar to ~ for home directory? There's a fairly standard two or three-semester curriculum for introductory quantum field theory, which covers topics such as:   classical field theory background canonical quantization, path integrals the Dirac field quantum electrodynamics computing $S$-matrix elements in perturbation theory, decay rates, cross sections renormalization at one loop Yang-Mills theory spontaneous symmetry breaking the Standard Model   What is a good, complete and comprehensive book that covers topics such as these? Why can't my subclass access a protected variable of its superclass, when it's in a different package? php function for collating external variables into a single object regardless of GET or POST I recall reviewing someone else's PHP code once and he had a function or class method that rolled all GET and POST variables into a single plain old object that could then be passed around. If the same name-value pair appeared in both GET and POST, POST would win.  Is there a well-coded PHP add-on out there of any sort that does exactly this? The sine inequality $\frac2\pi x \le \sin x \le x$ for $0<x<\frac\pi2$ So I can start from len(collection) and end in collection[0].  I also want to be able to access the loop index. What's the best way to find the inverse of datetime.isocalendar()? Defining coordinate reference system with rotation in GeoServer? I am using GeoServer and have a layer in EPSG:900913 ("Google Mercator").  I need to "rotate" the map around certain point (say, 1500000, 7000000) by certain degree (say, 30 degrees clockwise). How could I define such a coordinate system based on EPSG:900913?  GeoServer's  does not work for my purposes as I need to tile the map later on.  As far as I understand this, my only option is to define an own coordinate system. For GeoServer I'd need to . The configuration seems to be straightforward, but I have a difficulty defining my rotated CRS in .  I am wondering how to apply a rotation around certain point onto a CRS like Google Mercator:  PROJCS["WGS84 / Google Mercator",    GEOGCS["WGS 84",      DATUM["World Geodetic System 1984",        SPHEROID["WGS 84", 6378137.0, 298.257223563, AUTHORITY["EPSG","7030"]],        AUTHORITY["EPSG","6326"]],      PRIMEM["Greenwich", 0.0, AUTHORITY["EPSG","8901"]],      UNIT["degree", 0.017453292519943295],      AXIS["Longitude", EAST],      AXIS["Latitude", NORTH],      AUTHORITY["EPSG","4326"]],    PROJECTION["Mercator_1SP"],    PARAMETER["semi_minor", 6378137.0],    PARAMETER["latitude_of_origin", 0.0],    PARAMETER["central_meridian", 0.0],    PARAMETER["scale_factor", 1.0],    PARAMETER["false_easting", 0.0],    PARAMETER["false_northing", 0.0],    UNIT["m", 1.0],    AXIS["x", EAST],    AXIS["y", NORTH],    AUTHORITY["EPSG","900913"]]   My questions, specifically:   How to write a WKT which transform an existing CRS? My guess would be that I need a new PROJCS wrapping an existing one and adding a PROJECTION clause. How would I found out the projection id (like Mercator_1SP above) and the required parameters (the PARAMETER clauses)? Can I "reference" EPSG:900913 in CRS WKT instead of copy-pasting the whole PROJCS clause? What governor limits impact Apex Describe methods? Are there any governor limits, or considerations that I should be aware of when using Apex Describe methods?  So for example, the author of this blog post uses the structure below to get the record type instead of doing a soql query.     //Generate a map of tokens for the sObjects in your organization Map gd = Schema.getGlobalDescribe();  //Retrieve the describe result for the desired object DescribeSObjectResult result = gd.get('Account').getDescribe();  //Generate a map of tokens for all the Record Types for the desired object Map recordTypeInfo = result.getRecordTypeInfosByName(); system.debug('RECORD TYPES:' + recordTypeInfo);  //Retrieve the record type id by name String recordTypeId = recordTypeInfo.get('RECORDTYPE_NAME').getRecordTypeId(); Can't execute terminal commands: "the command 'sudo' is available in '/usr/bin/sudo'" How do I add arrowheads to circular arcs? Sending email with PHP from an SMTP server Why I can't edit "Your Communities" list in stackexchange.com and Area 51? I can edit &quot;YOUR COMMUNITIES&quot; in the upper left drop-down menu from any of my communities: (e.g. )    But in  portal there's no &quot;edit&quot; link:    Why is that and how can I edit the list in  portal? How to reconcile the cashless human/Federation society with human traders and merchants I have a dual boot laptop (Windows 10). I ran general updates and now my Ubuntu won't boot.   I ran in recovery mode and still it freezes in the same place.      Kernel panic – not syncing: Attempted to kill init! exit code=0x00007f00 Which singular names ending in “s” form possessives with only a bare apostrophe?