# How to silence a pipeline?

**URL:** <https://discourse.julialang.org/t/how-to-silence-a-pipeline/90726>\
**Category:** General Usage\
**Tags:** question\
**Created:** [November 23, 2022, 6:47pm UTC](https://discourse.julialang.org/t/how-to-silence-a-pipeline/90726 "2022-11-23T18:47:33Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![marianoarnaiz](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/marianoarnaiz/32/19377_2.png) [@marianoarnaiz](https://discourse.julialang.org/u/marianoarnaiz)\
**Post date:** [November 23, 2022, 6:47pm UTC](https://discourse.julialang.org/t/how-to-silence-a-pipeline/90726/1 "2022-11-23T18:47:33Z")

</div>

Hi all.  
I am running an external fortran code that reads an input file and outputs another. While the program runs it prints some lines.

I am calling the program with run and pipeline:

> run(pipeline(`cat in.love`,`./love`));

And this lines get printed in the Julia terminal too…

> enter input model file:  
> enter output file:  
> enter eigfn output file:  
> WARNING!!! Is your input in MKS units???  
> corrected for WARNING as follows:  
> r,rho,vpv,vsv,vph,vsh multiplied by 1000 to  
> convert to MKS units.  
> enter eps  
> frequency spacing is computed as 1.0/timelength  
> if used for synthetics, time length must be dt \* 2\*\*n  
> enter power of two (e.g. 8) or 0 for custom list of periods:  
> Give periods, end with 0:  
> enter highest mode number (fundamental=0):  
> enter min, max Vphase (km/s):  
> the modes file contains eigenvectors at the top of the model  
> too many layers will use up lots of disk space  
> how many layers (from top) to eigenfunction file?  
> Custom list of frequencies (Hz):  
> 1 0.0500  
> 2 0.0455  
> 3 0.0435  
> 4 0.0400  
> 5 0.0357  
> 6 0.0333  
> 7 0.0312  
> 8 0.0286  
> 9 0.0263  
> 10 0.0244  
> 11 0.0227  
> 12 0.0208  
> 13 0.0192  
> 14 0.0179  
> 15 0.0164  
> 16 0.0152  
> 17 0.0139  
> 18 0.0128  
> 19 0.0119  
> 20 0.0110  
> 21 0.0101  
> 22 0.0093  
> 23 0.0086  
> 24 0.0080  
> 25 0.0074  
> 26 0.0068  
> 27 0.0063  
> 28 0.0058  
> 29 0.0053  
> 30 0.0049  
> 31 0.0046  
> 32 0.0042  
> 33 0.0039  
> 34 0.0036  
> 35 0.0033  
> 36 0.0031  
> 37 0.0028  
> 38 0.0026  
> 39 0.0024  
> 40 0.0022  
> Computation progress  
> If mmax exceeds nbran= 8 it is truncated
> 
> ```
> i Hz mmin mmax
> 1 0.050000 0 20
> 2 0.045455 0 19
> 3 0.043478 0 18
> 4 0.040000 0 17
> 5 0.035714 0 15
> 6 0.033333 0 14
> 7 0.031250 0 13
> 8 0.028571 0 12
> 9 0.026316 0 11
> 10 0.024390 0 10
> 11 0.022727 0 9
> 12 0.020833 0 9
> 13 0.019231 0 8
> 14 0.017857 0 8
> 15 0.016393 0 7
> 16 0.015152 0 6
> 17 0.013889 0 6
> 18 0.012821 0 6
> 19 0.011905 0 5
> 20 0.010989 0 5
> 21 0.010101 0 5
> 22 0.009346 0 4
> 23 0.008621 0 4
> 24 0.008000 0 4
> 25 0.007353 0 3
> 26 0.006803 0 3
> 27 0.006289 0 3
> 28 0.005780 0 3
> 29 0.005348 0 3
> 30 0.004926 0 3
> 31 0.004566 0 2
> 32 0.004202 0 2
> 33 0.003891 0 2
> 34 0.003584 0 2
> 35 0.003311 0 2
> 36 0.003058 0 2
> 37 0.002825 0 2
> 38 0.002604 0 2
> 39 0.002410 0 1
> 40 0.002198 0 1
> 
> ```
> 
> Note: The following floating-point exceptions are signalling: IEEE\_UNDERFLOW\_FLAG

Is there a way to stop showing this output in the Julia screen?

Thanks!

---

<div class="post-metadata">

**Author:** ![sgaure](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/sgaure/32/14779_2.png) [@sgaure](https://discourse.julialang.org/u/sgaure)\
**Post date:** [November 23, 2022, 10:49pm UTC](https://discourse.julialang.org/t/how-to-silence-a-pipeline/90726/2 "2022-11-23T22:49:00Z")

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If your fortran program print to standard output, you can use the `stdout` keyword in pipeline:

```julia
run(pipeline(`myprogram`, stdout=devnull))

```

to redirect output to nowhere.

---

<div class="post-metadata">

**Author:** ![marianoarnaiz](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/marianoarnaiz/32/19377_2.png) [@marianoarnaiz](https://discourse.julialang.org/u/marianoarnaiz)\
**Post date:** [November 24, 2022, 2:23pm UTC](https://discourse.julialang.org/t/how-to-silence-a-pipeline/90726/3 "2022-11-24T14:23:41Z")

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> [@sgaure](#):
>
> `stdout`

I am running the same lines with the added stdout and get an error :(:

> ERROR: LoadError: MethodError: no method matching pipeline(::Cmd, ::Cmd; stdout=Base.DevNull())  
> Closest candidates are:  
> pipeline(::Base.AbstractCmd, ::Any) at /Applications/Julia-1.7.app/Contents/Resources/julia/share/julia/base/cmd.jl:337 got unsupported keyword argument “stdout”  
> pipeline(::Any, ::Any, ::Any, ::Any…) at /Applications/Julia-1.7.app/Contents/Resources/julia/share/julia/base/cmd.jl:358 got unsupported keyword argument “stdout”  
> pipeline(::Base.AbstractCmd; stdin, stdout, stderr, append) at /Applications/Julia-1.7.app/Contents/Resources/julia/share/julia/base/cmd.jl:321  
> …  
> Stacktrace:  
> [1] SWD\_Nolet(model::Matrix{Float64})  
> @ Main ~/Documents/JULIA/SWD\_Nolet/src/SWD\_Nolet.jl:13  
> [2] top-level scope  
> @ ~/Documents/JULIA/SWD\_Nolet/Call\_Nolet00.jl:43  
> [3] eval  
> @ ./boot.jl:373 [inlined]  
> [4] include\_string(mapexpr::typeof(identity), mod::Module, code::String, filename::String)  
> @ Base ./loading.jl:1196  
> in expression starting at /Users/omenbonum/Documents/JULIA/SWD\_Nolet/Call\_Nolet00.jl:43

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<div class="post-metadata">

**Author:** ![barucden](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/barucden/32/26154_2.png) [@barucden](https://discourse.julialang.org/u/barucden)\
**Post date:** [November 24, 2022, 2:42pm UTC](https://discourse.julialang.org/t/how-to-silence-a-pipeline/90726/4 "2022-11-24T14:42:02Z")

</div>

What about using an extra `pipeline`? Like so:

```julia
run(pipeline(pipeline(`cat in.love`, `./love`), stdout=devnull))

```

---

<div class="post-metadata">

**Author:** ![marianoarnaiz](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/marianoarnaiz/32/19377_2.png) [@marianoarnaiz](https://discourse.julialang.org/u/marianoarnaiz)\
**Post date:** [November 26, 2022, 8:23pm UTC](https://discourse.julialang.org/t/how-to-silence-a-pipeline/90726/5 "2022-11-26T20:23:45Z")

</div>

This Works well. I though the double pipeline might slow the process down, but it works equally fast.

All the fortran code has write(\*,6) and things like that, I guess why the first pipeline wont shut the stdout! Thanks