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StartProcess
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StartProcess

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StartProcess["executable"]

executes an external program, yielding a ProcessObject to represent the resulting subprocess.

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StartProcess[{"executable",arg1,arg2,…}]

executes an external program, passing it the specified arguments argi.

Details

  • StartProcess returns a ProcessObject if the process it specifies can be started; otherwise, it returns $Failed.
  • StartProcess can be used to interact with processes while they are running or to run "background tasks" without blocking the Wolfram Engine.
  • StartProcess returns immediately and does not wait for the started process to complete. Use RunProcess to wait for a process to complete.
  • In StartProcess[{"executable",arg1,arg2,…}], the argi are converted to strings using ToString.
  • The Wolfram Engine can communicate with a subprocess represented by a ProcessObject with functions like WriteLine, WriteString, BinaryWrite, ReadLine, ReadString, and BinaryRead.
  • The standard input, output, and error streams can be represented using ProcessConnection.
  • Information about the subprocess can be queried using ProcessStatus and ProcessInformation.
  • The following options can be given:
  • ProcessDirectoryInheritedinitial working directory
    ProcessEnvironmentInheritedenvironment variables to give the subprocess
  • By default, the subprocess will inherit its process directory and environment variables from the Wolfram Engine.
  • If the Wolfram Engine is terminated, the subprocess will be forced to close.
  • If any of the arguments argi are of the form "name"->value, they will be converted into the form "--name=value". If name is a single character, only one dash will be used.

Examples

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Basic Examples  (1)Summary of the most common use cases

Start the system shell process:

In[1]:=1
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https://wolfram.com/xid/09a7mpj8i-hp8oi3
Out[1]=1

Write a command into the system shell process:

In[2]:=2
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https://wolfram.com/xid/09a7mpj8i-6j3c93

Read the command output:

In[3]:=3
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https://wolfram.com/xid/09a7mpj8i-32mxq4
Out[3]=3

Check whether the process is running or not:

In[4]:=4
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https://wolfram.com/xid/09a7mpj8i-wfb484
Out[4]=4

Write an exit command into the shell process:

In[5]:=5
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https://wolfram.com/xid/09a7mpj8i-ovl1yg

Verify the program has actually finished:

In[6]:=6
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https://wolfram.com/xid/09a7mpj8i-g3788s
Out[6]=6

Possible Issues  (4)Common pitfalls and unexpected behavior

The right way to call StartProcess for a program plus its arguments is using a list:

In[1]:=1
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https://wolfram.com/xid/09a7mpj8i-c62gbc
Out[1]=1

Calling StartProcess with the command and arguments in a single string is not allowed:

In[2]:=2
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https://wolfram.com/xid/09a7mpj8i-ey721d
Out[2]=2

Also, calling StartProcess with the program arguments as arguments for StartProcess is not allowed:

In[3]:=3
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https://wolfram.com/xid/09a7mpj8i-5wu2d3
Out[3]=3

Special symbols like ~ and * are not converted using shell expansion, because StartProcess skips the shell:

In[1]:=1
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https://wolfram.com/xid/09a7mpj8i-tud8bc
Out[1]=1

Shell commands like dir, echo cannot be called directly on Windows because they are not binaries (however, they work on Unix systems because they are Unix binaries):

In[1]:=1
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https://wolfram.com/xid/09a7mpj8i-j9q8wd
Out[1]=1

Some commands might need to be called using absolute paths:

In[1]:=1
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https://wolfram.com/xid/09a7mpj8i-2a8cjg
Out[1]=1

Interactive Examples  (1)Examples with interactive outputs

Create an interactive console in the Wolfram Language. To test this example, first evaluate the cells. Then type any valid shell command in the input box and click the Go button:

In[1]:=1
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https://wolfram.com/xid/09a7mpj8i-cujonf
In[2]:=2
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https://wolfram.com/xid/09a7mpj8i-2pusal

Neat Examples  (1)Surprising or curious use cases

Start a new WolframKernel process for parallel computation:

In[1]:=1
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https://wolfram.com/xid/09a7mpj8i-eo3a0c
Out[1]=1
In[2]:=2
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https://wolfram.com/xid/09a7mpj8i-4u43op
Out[2]=2

Make the kernel process do a long computation and quit:

In[3]:=3
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https://wolfram.com/xid/09a7mpj8i-weany3
In[4]:=4
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https://wolfram.com/xid/09a7mpj8i-xc6bk6

Read the process output whenever it finishes:

In[5]:=5
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https://wolfram.com/xid/09a7mpj8i-862li0
Out[5]=5

Read any messages sent to the error stream:

In[6]:=6
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https://wolfram.com/xid/09a7mpj8i-lz0mbk
Out[6]=6
Wolfram Research (2014), StartProcess, Wolfram Language function, https://reference.wolfram.com/language/ref/StartProcess.html.
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Wolfram Research (2014), StartProcess, Wolfram Language function, https://reference.wolfram.com/language/ref/StartProcess.html.

Text

Wolfram Research (2014), StartProcess, Wolfram Language function, https://reference.wolfram.com/language/ref/StartProcess.html.

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Wolfram Research (2014), StartProcess, Wolfram Language function, https://reference.wolfram.com/language/ref/StartProcess.html.

CMS

Wolfram Language. 2014. "StartProcess." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/StartProcess.html.

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Wolfram Language. 2014. "StartProcess." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/StartProcess.html.

APA

Wolfram Language. (2014). StartProcess. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/StartProcess.html

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Wolfram Language. (2014). StartProcess. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/StartProcess.html

BibTeX

@misc{reference.wolfram_2025_startprocess, author="Wolfram Research", title="{StartProcess}", year="2014", howpublished="\url{https://reference.wolfram.com/language/ref/StartProcess.html}", note=[Accessed: 18-April-2025 ]}

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@misc{reference.wolfram_2025_startprocess, author="Wolfram Research", title="{StartProcess}", year="2014", howpublished="\url{https://reference.wolfram.com/language/ref/StartProcess.html}", note=[Accessed: 18-April-2025 ]}

BibLaTeX

@online{reference.wolfram_2025_startprocess, organization={Wolfram Research}, title={StartProcess}, year={2014}, url={https://reference.wolfram.com/language/ref/StartProcess.html}, note=[Accessed: 18-April-2025 ]}

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@online{reference.wolfram_2025_startprocess, organization={Wolfram Research}, title={StartProcess}, year={2014}, url={https://reference.wolfram.com/language/ref/StartProcess.html}, note=[Accessed: 18-April-2025 ]}