Jenkins is unable to run arc - jenkins

Question

Here is a brief description of my current setup. We use
Git : revision control system
Phabricator : Code Review
Jenkins : for Continuous Integration and running builds.
Plugins : Phabricator differential, windows slaves plugin
Jenkins setup has a linux master , and windows & Mac Slaves. I also have Phabricator Differential enabled on the projects , and arcanist installed on all the Jenkins Nodes.
While Running Windows Projects,the build fails with the following error message that says it can not find arc in the specified folder.I m however able to run arc from the folder manually, I have made sure that the environment variables are set properly.Has anyone run into this issue before ?
`The system cannot find the file specified
FATAL: command execution failed
java.io.IOException: Cannot run program "sh" (in directory "C:\Users\Jenkins\workspace\windows_project"): CreateProcess error=2, The system cannot find the file specified
at java.lang.ProcessBuilder.start(ProcessBuilder.java:1048)
at hudson.Proc$LocalProc.<init>(Proc.java:244)
at hudson.Proc$LocalProc.<init>(Proc.java:216)
at hudson.Launcher$LocalLauncher.launch(Launcher.java:816)
at hudson.Launcher$ProcStarter.start(Launcher.java:382)
at hudson.Launcher$RemoteLaunchCallable.call(Launcher.java:1149)
at hudson.Launcher$RemoteLaunchCallable.call(Launcher.java:1114)
at hudson.remoting.UserRequest.perform(UserRequest.java:121)
at hudson.remoting.UserRequest.perform(UserRequest.java:49)
at hudson.remoting.Request$2.run(Request.java:325)
at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:68)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at hudson.remoting.Engine$1$1.run(Engine.java:69)
at java.lang.Thread.run(Thread.java:745)
at ......remote call to winbuild2(Native Method)
at hudson.remoting.Channel.attachCallSiteStackTrace(Channel.java:1361)
at hudson.remoting.UserResponse.retrieve(UserRequest.java:221)
at hudson.remoting.Channel.call(Channel.java:753)
at hudson.Launcher$RemoteLauncher.launch(Launcher.java:929)
at hudson.Launcher$ProcStarter.start(Launcher.java:382)
at hudson.tasks.CommandInterpreter.perform(CommandInterpreter.java:97)
at hudson.tasks.CommandInterpreter.perform(CommandInterpreter.java:66)
at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:779)
at hudson.model.Build$BuildExecution.build(Build.java:205)
at hudson.model.Build$BuildExecution.doRun(Build.java:162)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:537)
at hudson.model.Run.execute(Run.java:1744)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
at hudson.model.ResourceController.execute(ResourceController.java:98)
at hudson.model.Executor.run(Executor.java:374)
Caused by: java.io.IOException: CreateProcess error=2, The system cannot find the file specified
at java.lang.ProcessImpl.create(Native Method)
at java.lang.ProcessImpl.<init>(ProcessImpl.java:386)
at java.lang.ProcessImpl.start(ProcessImpl.java:137)
at java.lang.ProcessBuilder.start(ProcessBuilder.java:1029)
at hudson.Proc$LocalProc.<init>(Proc.java:244)
at hudson.Proc$LocalProc.<init>(Proc.java:216)
at hudson.Launcher$LocalLauncher.launch(Launcher.java:816)
at hudson.Launcher$ProcStarter.start(Launcher.java:382)
at hudson.Launcher$RemoteLaunchCallable.call(Launcher.java:1149)
at hudson.Launcher$RemoteLaunchCallable.call(Launcher.java:1114)
at hudson.remoting.UserRequest.perform(UserRequest.java:121)
at hudson.remoting.UserRequest.perform(UserRequest.java:49)
at hudson.remoting.Request$2.run(Request.java:325)`
arc error message:
[windows_box_testing] $ arc call-conduit differential.querydiffs
The system cannot find the file specified
FATAL: Cannot run program "arc" (in directory "C:\Users\Jenkins\workspace\windows_box_testing"): CreateProcess error=2, The system cannot find the file specified
java.io.IOException: Cannot run program "arc" (in directory "C:\Users\Jenkins\workspace\windows_box_testing"): CreateProcess error=2, The system cannot find the file specified
at java.lang.ProcessBuilder.start(ProcessBuilder.java:1048)
at hudson.Proc$LocalProc.<init>(Proc.java:244)
at hudson.Proc$LocalProc.<init>(Proc.java:216)
at hudson.Launcher$LocalLauncher.launch(Launcher.java:816)

Answer 1

As mentioned by Anders, the log is indicating Cannot run program "sh". When you run arc on the box, are you running it from Windows Command Prompt or are you opening a linux-like shell.
For example, when I need to run arc commands on Windows, while logged in, I usually launch Git Bash, which does have a version of sh. However, to get that machine up and going as a build server with arc, I needed to install Cygwin and make Jenkins run the script in there.
I hope this helps.