mono Process.Start how to find bash?

Question

In my webapp i do the below. I know its correct because i tried 1) dumping start_sz to a text file 2) su www-data 3) copy/paste the extract string and it worked.

var start_sz = string.Format(@"bash -c 'ln ""{2}/{0}"" ""{2}/{1}""'", fn, newfn, System.IO.Directory.GetCurrentDirectory());
Process.Start(start_sz);

I get the exception below so with reasoning above i believe its saying bash cannot be found.

Cannot find the specified file

at System.Diagnostics.Process.Start_shell (System.Diagnostics.ProcessStartInfo startInfo, System.Diagnostics.Process process) [0x00000] in :0

at System.Diagnostics.Process.Start_common (System.Diagnostics.ProcessStartInfo startInfo, System.Diagnostics.Process process) [0x00000] in :0

at System.Diagnostics.Process.Start (System.Diagnostics.ProcessStartInfo startInfo) [0x00000] in :0

at System.Diagnostics.Process.Start (System.String fileName) [0x00000] in :0

at MySite.QueueManager.MakeLink (System.String fn) [0x00000] in :0

at MySite.QueueManager.ImageQueue2 () [0x00000] in :0

at MySite.QueueManager.ImageQueue () [0x00000] in :0

So, how do i fix this? basically i need to create a hardlink (soft is ok too) at run time in my asp.net app.

I thought maybe i need the full bash path so i tried /bin/bash -c however that didn't work either.

Answer 1

Why not call ln directly? Without bash?

Process.Start("ln", params);

Also you may need to specify the full path:

Process.Start("/bin/ln", params);

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In fact, Process.Start("bash") works for me, thus check $PATH environment variable, etc.

Answer 2

No, you know it's correct when used from a shell. That shell will take the path into account, unlike Process.Start.

Just specify the full path to bash, which is almost certainly /bin/bash.