How do you execute an arbitrary native command from a string

Question

I can express my need with the following scenario  Write a function that accepts a string to be run as a native command    It s not too far fetched of an idea  if you re interfacing with other command-line utilities from elsewhere in the company that supply you with a command to run verbatim  Because you don t control the command  you need to accept any valid command as input  These are the main hiccups I ve been unable to easily overcome    The command might execute a program living in a path with a space in it    command     C  Program Files TheProg Runit exe  Hello    The command may have parameters with spaces in them    command    echo  hello world      The command might have both single and double ticks    command    echo   it  s        Is there any clean way of accomplishing this  I ve only been able to devise lavish and ugly workarounds  but for a scripting language I feel like this should be dead simple

User · Answer

The accepted answer wasn t working for me when trying to parse the registry for uninstall strings  and execute them  Turns out I didn t need the call to Invoke-Expression after all   I finally came across this nice template for seeing how to execute uninstall strings    path    HKLM  SOFTWARE Wow6432Node Microsoft Windows CurrentVersion Uninstall   app    MyApp   apps      Get-ChildItem  path        Where-Object -FilterScript     getvalue  DisplayName   -like  app         ForEach-Object -process   apps Set Item             getvalue  UninstallString               getvalue  DisplayName           foreach   uninstall string in  apps GetEnumerator           uninstall app   uninstall arg    uninstall string name split           amp   uninstall app  uninstall arg     This works for me  namely because  app is an in house application that I know will only have two arguments  For more complex uninstall strings you may want to use the join operator  Also  I just used a hash-map  but really  you d probably want to use an array   Also  if you do have multiple versions of the same application installed  this uninstaller will cycle through them all at once  which confuses MsiExec exe  so there s that too

User · Answer

If you want to use the call operator  the arguments can be an array stored in a variable    prog    c  windows system32 cmd exe   myargs     c   dir    x   amp   prog  myargs   The call operator works with ApplicationInfo objects too    prog   get-command cmd  myargs   -split   c dir  x   amp   prog  myargs

User · Answer

Invoke-Expression  also aliased as iex  The following will work on your examples  2 and  3   iex  command   Some strings won t run as-is  such as your example  1 because the exe is in quotes  This will work as-is  because the contents of the string are exactly how you would run it straight from a Powershell command prompt    command    C  somepath someexe exe somearg  iex  command   However  if the exe is in quotes  you need the help of  amp  to get it running  as in this example  as run from the commandline    gt  gt   amp  C  Program Files Some Product SomeExe exe   C  some other path file ext    And then in the script    command     C  Program Files Some Product SomeExe exe   C  some other path file ext   iex   amp   command    Likely  you could handle nearly all cases by detecting if the first character of the command string is    like in this naive implementation   function myeval  command        if   command 0  -eq        iex   amp   command        else   iex  command       But you may find some other cases that have to be invoked in a different way  In that case  you will need to either use try  catch    perhaps for specific exception types messages  or examine the command string   If you always receive absolute paths instead of relative paths  you shouldn t have many special cases  if any  outside of the 2 above

User · Answer

Please also see this Microsoft Connect report on essentially  how blummin  difficult it is to use PowerShell to run shell commands  oh  the irony    http   connect microsoft com PowerShell feedback details 376207   They suggest using --  as a way to force PowerShell to stop trying to interpret the text to the right   For example   MSBuild  t Publish --   p TargetDatabaseName  MyDatabase  TargetConnectionString  Data Source    Integrated Security True   p SqlPublishProfilePath  Deploy publish xml  Database sqlproj

[scripting] How do you execute an arbitrary native command from a string?

Examples related to scripting

Examples related to powershell