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8. Running Gmsh

8.1 Interactive mode  
8.2 Non-interactive mode  
8.3 Command-line options  
8.4 Mouse actions  
8.5 Keyboard shortcuts  


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8.1 Interactive mode

Gmsh's first operating mode is the `interactive graphical mode'. To launch Gmsh in interactive mode, just click or double-click on the Gmsh icon (Windows and Mac), or type

 
> gmsh

at your shell prompt in a terminal (Unix). This will open two windows: the graphic window (with a status bar at the bottom) and the menu window (with a menu bar and some context-dependent buttons).

To open the first tutorial file (see section 7. Tutorial), select the `File->Open' menu, and choose `t1.geo' in the input field. When using a terminal, you can also specify the file name directly on the command line, i.e.:

 
> gmsh t1.geo

To perform the mesh generation, go to the mesh module (by selecting `Mesh' in the module menu) and choose the required dimension in the context-dependent buttons (`1D' will mesh all the lines; `2D' will mesh all the surfaces--as well as all the lines if `1D' was not called before; `3D' will mesh all the volumes--and all the surfaces if `2D' was not called before). To save the resulting mesh in the current mesh format, choose `Save' in the context-dependent buttons, or select the appropriate format with the `File->Save as' menu. The default mesh file name is based on the name of the first input file on the command line (or `untitled' if there wasn't any input file given), with an appended extension depending on the mesh format(5).

To create a new geometry or to modify an existing geometry, select 'Geometry' in the module menu, and follow the context-dependent buttons. For example, to create a spline, select `Elementary', `Add', `New' and `Spline'. You will then be asked to select a list of points, and to type e to finish the selection (or q to abort it). Once the interactive command is completed, a text string is automatically added at the end of the current project file. You can edit this project file by hand at any time by pressing the `Edit' button in the `Geometry' menu and then reloading the project by pressing `Reload'. For example, it is often faster to define variables and points directly in the project file, and then use the graphical user interface to define the lines, the surfaces and the volumes interactively.

Several files can be loaded simultaneously in Gmsh. The first one defines the project, while the others are appended (`merged') to this project. You can merge such files with the `File->Merge' menu, or by directly specifying the names of the files on the command line. For example, to merge the post-processing views contained in the files `view1.pos' and `view2.pos' together with the geometry of the first tutorial `t1.geo', you can type the following command:

 
> gmsh t1.geo view1.pos view2.pos

In the Post-Processing module (select `Post-Processing' in the module menu), two view buttons will appear, respectively labeled `a scalar map' and `a vector map'. A mouse click on the name will toggle the visibility of the selected view, while a click on the arrow button on the right will provide access to the view's options. If you want the modifications made to one view to affect also all the other views, select the `Apply next changes to all views' or `Force same options for all views' option in the `Tools->Options->Post-processing' menu.

Note that all the options specified interactively can also be directly specified in the ASCII input files. All available options, with their current values, can be saved into a file by selecting `File->Save as->Gmsh options', or simply viewed by pressing the `?' button in the status bar. To save the current options as your default preferences for all future Gmsh sessions, use the `Tools->Options->Save' button.


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8.2 Non-interactive mode

Gmsh's second operating mode is the non-interactive (or `batch') mode. In this mode, there is no graphical user interface, and all operations are performed without any user interaction(6). For example, to mesh the first tutorial in non-interactive mode, just type:

 
> gmsh t1.geo -2

To mesh the same example, but with the background mesh available in the file `bgmesh.pos', type:

 
> gmsh t1.geo -2 -bgm bgmesh.pos

For the list of all command-line options, see 8.3 Command-line options.


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8.3 Command-line options

Geometry options:

-0
parse input files, output unrolled geometry, and exit

Mesh options:

-1, -2, -3
perform batch 1D, 2D and 3D mesh generation
-saveall
save all elements (discard physical group definitions)
-o file
specify mesh output file name
-format string
set output mesh format (msh, unv, gref)
-algo string
select 2D mesh algorithm (iso, tri, aniso, netgen)
-smooth int
set mesh smoothing
-optimize
optimize quality of tetrahedral elements
-order int
set the order of the generated elements (1, 2)
-scale float
set global scaling factor
-meshscale float
set mesh scaling factor
-clscale float
set characteristic length scaling factor
-rand float
set random perturbation factor
-bgm file
load backround mesh from file
-constrain
constrain background mesh with characteristic lengths
-histogram
print mesh quality histogram
-extrude
use old extrusion mesh generator
-recombine
recombine meshes from old extrusion mesh generator
-interactive
display 2D mesh construction interactively

Post-processing options:

-noview
hide all views on startup
-link int
select link mode between views (0, 1, 2, 3, 4)
-smoothview
smooth views
-combine
combine input views into multi-time-step ones

Display options:

-nodb
disable double buffering
-fontsize int
specify the font size for the GUI
-scheme string
specify FLTK GUI scheme
-display string
specify display

Other options:

-a, -g, -m, -s, -p
start in automatic, geometry, mesh, solver or post-processing mode
-pid
print pid on stdout
-v int
set verbosity level
-string "string"
parse string before project file
-option file
parse option file before GUI creation
-convert file file
perform batch conversion of views and meshes into latest file formats
-version
show version number
-info
show detailed version information
-help
show this message


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8.4 Mouse actions

In the following, for a 2 button mouse, Middle button = Shift+Left button. For a 1 button mouse, Middle button = Shift+Left button and Right button = Alt+Left button.

Move the mouse:

Left button:

Ctrl+Left button: start (anisotropic) rubber zoom

Middle button:

Ctrl+Middle button: orthogonalize display

Right button:

Ctrl+Right button: reset to default viewpoint


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8.5 Keyboard shortcuts

Keyboard shortcuts:

Left arrow
go to previous time step

Right arrow
go to next time step

Up arrow
make previous view visible

Down arrow
make next view visible

<
go back to previous context

>
go forward to next context

0
Esc
reload geometry input file

1
F1
mesh curves

2
F2
mesh surfaces

3
F3
mesh volumes

Alt+a
hide/show small axes

Shift+a
raise (show) all open windows

Alt+Shift+a
hide/show big moving axes

Alt+b
hide/show all bounding boxes

Alt+c
loop through predefined color schemes

Alt+d
change mesh display mode (solid/wireframe)

Shift+d
decrease animation delay

Ctrl+Shift+d
increase animation delay

Alt+f
change redraw mode (fast/full)

g
go to geometry module

Shift+g
show geometry options

Alt+h
hide/show all post-processing views

Alt+i
hide/show all post-processing scales

Shift+i
show statistics window

Alt+l
hide/show geometry lines

Alt+Shift+l
hide/show surface mesh edges

m
go to mesh module

Alt+m
change visibility of all mesh entities

Shift+m
show mesh options

Ctrl+m
merge file

Shift+n
show general options

Ctrl+n
new file

Alt+o
change projection mode (ortho/perspective)

Shift+o
show option window

Ctrl+o
open file

p
go to post-processor module

Alt+p
hide/show geometry points

Shift+p
show general post-processing options

Alt+Shift+p
hide/show mesh points

Ctrl+q
quit

Alt+s
hide/show geometry surfaces

Alt+Shift+s
hide/show mesh surfaces

Ctrl+s
save mesh in default format

Ctrl+Shift+s
save file as

Alt+t
loop through interval modes for all post-processing views

Alt+v
hide/show geometry volumes

Alt+Shift+v
hide/show mesh volumes

Alt+w
enable/disable all lighting

Shift+w
show current post-processing view options

Alt+x
set X view

Alt+y
set Y view

Alt+z
set Z view


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