# Consistent way to suppress solver output
**URL:** https://discourse.julialang.org/t/consistent-way-to-suppress-solver-output/20437
**Category:** Optimization (Mathematical)
**Created:** [February 4, 2019, 4:55pm UTC](https://discourse.julialang.org/t/consistent-way-to-suppress-solver-output/20437 "2019-02-04T16:55:20Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@ndinsmore](https://discourse.julialang.org/u/ndinsmore)
#### Post date: [February 4, 2019, 4:55pm UTC](https://discourse.julialang.org/t/consistent-way-to-suppress-solver-output/20437/1 "2019-02-04T16:55:21Z")
Is there a consistent way to suppress the solver output in JuMP v0.19 or MOI? It isn’t clear to me if there is.
---
### Author:  [@tkoolen](https://discourse.julialang.org/u/tkoolen)
#### Post date: [February 4, 2019, 6:55pm UTC](https://discourse.julialang.org/t/consistent-way-to-suppress-solver-output/20437/2 "2019-02-04T18:55:41Z")
Not really; it’s all handled through each individual solver’s options API. As a hack, I suppose you could use
```julia
redirect_stdout(devnull) do
# code here
end
```
but that doesn’t remove the overhead of the solver printing status info (which may or may not be a problem).
---
### Author:  [@anon43133060](https://discourse.julialang.org/u/anon43133060)
#### Post date: [February 4, 2019, 9:06pm UTC](https://discourse.julialang.org/t/consistent-way-to-suppress-solver-output/20437/3 "2019-02-04T21:06:07Z")
> [@tkoolen](#):
>
> redirect\_stdout(devnull) do
`devnull` is of type `IO` not `IOStream`:
```julia
ERROR: MethodError: no method matching redirect_stderr(::Base.DevNull)
Closest candidates are:
redirect_stderr() at stream.jl:1001
redirect_stderr(::Union{IOStream, Base.LibuvStream}) at stream.jl:995
redirect_stderr(::Function, ::Any) at stream.jl:1051
```
What’s the best way to convert from `IO` to `IOStream`?
---
### Author:  [@ndinsmore](https://discourse.julialang.org/u/ndinsmore)
#### Post date: [February 4, 2019, 9:28pm UTC](https://discourse.julialang.org/t/consistent-way-to-suppress-solver-output/20437/4 "2019-02-04T21:28:21Z")
The solution I ended up with was:
`redirect_stdout((()->optimize!(model)),open("/dev/null", "w"))`
---
### Author:  [@tkoolen](https://discourse.julialang.org/u/tkoolen)
#### Post date: [February 4, 2019, 9:32pm UTC](https://discourse.julialang.org/t/consistent-way-to-suppress-solver-output/20437/5 "2019-02-04T21:32:09Z")
Yep. Sorry, should have tested my code. Related issue: [Proposal: Allow DevNull to be used in redirect\_stdout · Issue #22879 · JuliaLang/julia · GitHub](https://github.com/JuliaLang/julia/issues/22879).
---
### Author:  [@hhaensel](https://discourse.julialang.org/u/hhaensel)
#### Post date: [January 31, 2020, 10:32am UTC](https://discourse.julialang.org/t/consistent-way-to-suppress-solver-output/20437/6 "2020-01-31T10:32:25Z")
Just came across this old problem. If you want to use parts of the output you can redirect stdout to a string:
```julia
function capture_stdout(f)
stdout_orig = stdout
(rd, wr) = redirect_stdout()
f()
close(wr)
redirect_stdout(stdout_orig)
read(rd, String)
end
s = capture_stdout() do
optimize!(model)
end
#print the summary (which starts with "Number of Iterations")
try
s[findlast("Number of Iterations", s)[1]:end] |> print
catch
print(s)
end
```
EDIT:
Digged a bit further and found that most solvers support some kind of [loglevel setting](https://www.isys.uni-stuttgart.de/lehre/lehrveranstaltungen/nmopt/Aufgaben/JuMP_Kurzbeschreibung.pdf), e.g.:
- Ipopt: “print\_level”
- Cbc: “LogLevel”
- Clp: “logLevel”
These options can be set either when initialising the model, e.g.
```julia
model = Model(with_optimizer(Ipopt.Optimizer, tol = 1e-8, max_iter = 1000, print_level = 1))`
```
or afterwards using the MOI Api (which is currently not so nicely documented …)
```julia
MOI.set(model, MOI.RawParameter("print_level"), 1)
```
---
### Author:  [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)
#### Post date: [October 27, 2020, 9:57am UTC](https://discourse.julialang.org/t/consistent-way-to-suppress-solver-output/20437/7 "2020-10-27T09:57:32Z")
Is this a portable solution or it works only in Linux/Mac ?
---
### Author:  [@odow](https://discourse.julialang.org/u/odow)
#### Post date: [October 27, 2020, 7:24pm UTC](https://discourse.julialang.org/t/consistent-way-to-suppress-solver-output/20437/8 "2020-10-27T19:24:15Z")
Use [`set_silent`](https://jump.dev/JuMP.jl/stable/solvers/#JuMP.set_silent):
```nohighlight
model = Model(Ipopt.Optimizer)
set_silent(model)
```
---
### Author:  [@MAJegh](https://discourse.julialang.org/u/MAJegh)
#### Post date: [December 26, 2021, 9:17pm UTC](https://discourse.julialang.org/t/consistent-way-to-suppress-solver-output/20437/9 "2021-12-26T21:17:56Z")
Had some trouble with this where output was still printed.
It was due to the C level output not being flushed before the stdout gets restored.
So might be helpful to call :
> Base.Libc.flush\_cstdio()
Can use the following to print to a file as well :
```julia
open("/dev/null", "w") do f
redirect_stdout(f) do
# redirect_stdio(stdout=f,stderr=f) do
optimize!(model)
Base.Libc.flush_cstdio()
end
end
```