How to update PATH variable permanently from Windows command line

Question

If I execute set PATH  PATH  C   Something  bin from the command line  cmd exe  and then execute echo  PATH  I see this string added to the PATH  If I close and open the command line  that new string is not in PATH   How can I update PATH permanently from the command line for all processes in the future  not just for the current process   I don t want to do this by going to System Properties   Advanced   Environment variables and update PATH there   This command must be executed from a Java application  please see my other question

User · Answer

For reference purpose  for anyone searching how to change the path via code  I am quoting a useful post by a Delphi programmer from this web page  http   www tek-tips com viewthread cfm qid 686382     TonHu  Programmer      22 Oct 03 17 57 I found where I read the original   posting  it s here    http   news jrsoftware org news innosetup isx msg02129          The excerpt of what you would need is this       You must specify the string  Environment  in LParam  In Delphi you d   do it this way    SendMessage HWND BROADCAST  WM SETTINGCHANGE  0  Integer PChar  Environment            It was suggested by Jordan Russell  http   www jrsoftware org  the   author of  a o   InnoSetup    Inno Setup is a free installer for   Windows programs  First introduced in 1997  Inno Setup today rivals   and even surpasses many commercial installers in feature set and   stability     I just would like more people to use InnoSetup        HTH

User · Answer

This Python-script    does exactly that       Show Modify Append registry env-vars  ie  PATH   and notify Windows-applications to pickup changes   First attempts to show modify HKEY LOCAL MACHINE  all users   and  if not accessible due to admin-rights missing  fails-back  to HKEY CURRENT USER  Write and Delete operations do not proceed to user-tree if all-users succeed   Syntax        prog                     Print all env-vars        prog   VARNAME           Print value for VARNAME        prog   VARNAME   VALUE   Set VALUE for VARNAME        prog    VARNAME  VALUE   Append VALUE in VARNAME delimeted with      i e  used for  PATH          prog   -VARNAME          Delete env-var value    Note that the current command-window will not be affected   changes would apply only for new command-windows       import winreg import os  sys  win32gui  win32con  def reg key tree  path  varname       return   s  s  s     tree  path  varname    def reg entry tree  path  varname  value       return   s  s     reg key tree  path  varname   value   def query value key  varname       value  type id   winreg QueryValueEx key  varname      return value  def yield all entries tree  path  key       i   0     while True          try              n v t   winreg EnumValue key  i              yield reg entry tree  path  n  v              i    1         except OSError              break    Expected  this is how iteration ends   def notify windows action  tree  path  varname  value       win32gui SendMessage win32con HWND BROADCAST  win32con WM SETTINGCHANGE  0   Environment       print  --- s  s     action  reg entry tree  path  varname  value    file sys stderr   def manage registry env vars varname None  value None       reg keys               HKEY LOCAL MACHINE   r SYSTEM CurrentControlSet Control Session Manager Environment              HKEY CURRENT USER   r Environment              for  tree name  path  in reg keys          tree   eval  winreg  s  tree name          try              with winreg ConnectRegistry None  tree  as reg                  with winreg OpenKey reg  path  0  winreg KEY ALL ACCESS  as key                      if not varname                          for regent in yield all entries tree name  path  key                               print regent                      else                          if not value                              if varname startswith  -                                    varname   varname 1                                   value   query value key  varname                                  winreg DeleteValue key  varname                                  notify windows  Deleted   tree name  path  varname  value                                  break     Don t propagate into user-tree                              else                                  value   query value key  varname                                  print reg entry tree name  path  varname  value                           else                              if varname startswith                                       varname   varname 1                                   value   query value key  varname          value                             winreg SetValueEx key  varname  0  winreg REG EXPAND SZ  value                              notify windows  Updated   tree name  path  varname  value                              break     Don t propagate into user-tree          except PermissionError as ex              print     Cannot access  s due to   s                          reg key tree name  path  varname   ex   file sys stderr          except FileNotFoundError as ex              print     Cannot find  s due to   s                          reg key tree name  path  varname   ex   file sys stderr   if   name       main         args   sys argv     argc   len args      if argc  gt  3          print   doc   format prog args 0    file sys stderr          sys exit        manage registry env vars  args 1      Below are some usage examples  assuming it has been saved in a file called setenv py somewhere in your current path  Note that in these examples i didn t have admin-rights  so the changes affected only my local user s registry tree    gt  REM    Print all env-vars  gt  setenv py    Cannot access HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control Session   Manager Environment PATH due to   WinError 5  Access is denied HKEY CURRENT USER Environment PATH           gt  REM    Query env-var   gt  setenv py PATH C  foo    Cannot access HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control Session   Manager Environment PATH due to   WinError 5  Access is denied    Cannot find HKEY CURRENT USER Environment PATH due to   WinError 2  The system cannot find the file specified   gt  REM    Set env-var   gt  setenv py PATH C  foo    Cannot access HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control Session   Manager Environment PATH due to   WinError 5  Access is denied ---Set HKEY CURRENT USER Environment PATH C  foo   gt  REM    Append env-var   gt  setenv py  PATH D  Bar    Cannot access HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control Session   Manager Environment PATH due to   WinError 5  Access is denied ---Set HKEY CURRENT USER Environment PATH C  foo D  Bar   gt  REM    Delete env-var   gt  setenv py -PATH    Cannot access HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control Session   Manager Environment PATH due to   WinError 5  Access is denied ---Deleted HKEY CURRENT USER Environment PATH       Adapted from  http   code activestate com recipes 416087-persistent-environment-variables-on-windows

User · Answer

In a corporate network  where the user has only limited access and uses portable apps  there are these command line tricks    Query the user env variables  reg query  HKEY CURRENT USER Environment   Use  HKEY LOCAL MACHINE SYSTEM CurrentControlSet Control Session Manager Environment  for LOCAL MACHINE  Add new user env variable  reg add  HKEY CURRENT USER Environment   v shared dir  d  c  shared   t REG SZ  Use REG EXPAND SZ for paths containing other    variables  Delete existing env variable  reg delete  HKEY CURRENT USER Environment   v shared dir

User · Answer

You can use   setx PATH   PATH  C   Something  bin    However  setx will truncate the stored string to 1024 bytes  potentially corrupting the PATH    M will change the PATH in HKEY LOCAL MACHINE instead of HKEY CURRENT USER  In other words  a system variable  instead of the user s  For example   SETX  M PATH   PATH  C  your path with spaces    You have to keep in mind  the new PATH is not visible in your current cmd exe    But if you look in the registry or on a new cmd exe with  set p  you can see the new value

User · Answer

The documentation on how to do this can be found on MSDN  The key extract is this      To programmatically add or modify system environment variables  add them to the HKEY LOCAL MACHINE System CurrentControlSet Control Session Manager Environment registry key  then broadcast a WM SETTINGCHANGE message with lParam set to the string  Environment   This allows applications  such as the shell  to pick up your updates    Note that your application will need elevated admin rights in order to be able to modify this key   You indicate in the comments that you would be happy to modify just the per-user environment  Do this by editing the values in HKEY CURRENT USER Environment  As before  make sure that you broadcast a WM SETTINGCHANGE message   You should be able to do this from your Java application easily enough using the JNI registry classes

User · Answer

I caution against using the command  setx PATH   PATH  C  Something bin    to modify the PATH variable because of a  feature  of its implementation  On many  most   installations these days the variable will be lengthy - setx will truncate the stored string to 1024 bytes  potentially corrupting the PATH  see the discussion here     I signed up specifically to flag this issue  and so lack the site reputation  to directly comment on the answer posted on May 2  12  My thanks to beresfordt for adding such a comment

User · Answer

This script  http   www autohotkey com board topic 63210-modify-system-path-gui    includes all the necessary Windows API calls which can be refactored for your needs  It is actually an AutoHotkey GUI to change the System PATH easily  Needs to be run as an Administrator

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