How do I set parameters in Gurobi?

You have several options to set parameters in the Python interface.  Here are a few options to set the TimeLimit parameter:

m.Params.TimeLimit = 100.0
m.setParam(GRB.Param.TimeLimit, 100.0)
m.setParam("TimeLimit", 100.0)

For more details, please see Parameter Examples.

For details for each API, please see the Parameter Examples section of the Reference Manual.

error = GRBsetdblparam(GRBgetenv(model), GRB_DBL_PAR_TIMELIMIT, 100.0);
error = GRBsetdblparam(GRBgetenv(model), "TimeLimit", 100.0);

GRBModel *m = ...; 
m->set(GRB_DoubleParam_TimeLimit, 100.0);
m->set("TimeLimit", "100.0");

GRBModel m = ...;
m.Parameters.TimeLimit = 100.0;
m.Set(GRB.DoubleParam.TimeLimit, 100.0);
m.Set("TimeLimit", "100.0");

GRBModel m = ...;
m.set(GRB.DoubleParam.TimeLimit, 100.0);
m.set("TimeLimit", "100.0");

params.timelimit = 100;
params.TIME_LIMIT = 100;

params <- list(TimeLimit=100)
params <- list(TIME_LIMIT = 100)

GRBModel m = ...
m.Parameters.TimeLimit = 100.0
m.Set("TimeLimit", "100.0")

For example:

> gurobi_cl TimeLimit=100 /opt/gurobi1001/linux64/examples/data/coins.lp

For further details, see How do I use the Gurobi Command Line Interface (gurobi_cl)?

Another option is through a gurobi.env file.

Whenever the Gurobi library starts, it will look for gurobi.env in the current working directory and will apply any parameter changes contained therein. This is true whether the Gurobi library is invoked from the command-line tool, from the interactive shell, or from any of the Gurobi APIs.

Parameter settings are stored one per line in this file, with the parameter name first, followed by at least one space, followed by the desired value. Lines beginning with the # sign are comments and are ignored. To give an example, the following (Linux) commands:

> echo "Threads 1" > gurobi.env
> gurobi_cl /opt/gurobi1001/linux64/examples/data/coins.lp
Set parameter Threads to value 1
Read parameters from file gurobi.env
Set parameter LogFile to value "gurobi.log"
Using license file c:\gurobi\gurobi.lic
Using gurobi.env file
Gurobi Optimizer version 12.0.0 build v12.0.0rc1 (win64 - Windows 10.0 (19045.2))
Copyright (c) 2024, Gurobi Optimization, LLC
Read LP format model from file C:\gurobi1200\win64\examples\data\coins.lp
Reading time = 0.00 seconds
: 4 rows, 9 columns, 16 nonzeros
Using Gurobi shared library C:\gurobi1200\win64\bin\gurobi120.dll
CPU model: 11th Gen Intel(R) Core(TM) i7-1165G7 @ 2.80GHz, instruction set [SSE2|AVX|AVX2|AVX512]
Thread count: 4 physical cores, 8 logical processors, using up to 1 threads
Non-default parameters:
Threads  1
Optimize a model with 4 rows, 9 columns and 16 nonzeros
Model fingerprint: 0x06e334a4
Variable types: 4 continuous, 5 integer (0 binary)
Coefficient statistics:
 Matrix range     [6e-02, 7e+00]
 Objective range  [1e-02, 1e+00]
 Bounds range     [5e+01, 1e+03]
 RHS range        [0e+00, 0e+00]
Found heuristic solution: objective -0.0000000
Presolve removed 1 rows and 5 columns
Presolve time: 0.00s
Presolved: 3 rows, 4 columns, 9 nonzeros
Variable types: 0 continuous, 4 integer (0 binary)
Found heuristic solution: objective 25.2000000
Root relaxation: objective 1.134615e+02, 2 iterations, 0.00 seconds (0.00 work units)
   Nodes    |    Current Node    |     Objective Bounds      |     Work
Expl Unexpl |  Obj  Depth IntInf | Incumbent    BestBd   Gap | It/Node Time
    0     0  113.46154    0    1   25.20000  113.46154   350%     -    0s
H    0     0                     112.5000000  113.46154  0.85%     -    0s
H    0     0                     113.3000000  113.46154  0.14%     -    0s
H    0     0                     113.4500000  113.46154  0.01%     -    0s
    0     0  113.46154    0    1  113.45000  113.46154  0.01%     -    0s
Explored 1 nodes (2 simplex iterations) in 0.01 seconds (0.00 work units)
Thread count was 1 (of 8 available processors)
Solution count 5: 113.45 113.3 112.5 ... -0
Optimal solution found (tolerance 1.00e-04)
Best objective 1.134500000000e+02, best bound 1.134500000000e+02, gap 0.0000%

would read the new value of the Threads parameter from gurobi.env and then optimize model coins.lp using one thread. Note that if the same parameter is changed in both gurobi.env and in your program (or through the Gurobi command-line tool), the value from gurobi.env will be overridden.