# Recorder Commands

<noinclude>This command is used to generate a recorder object which is to monitor what is happening during the analysis and generate output for the user.

```tcl recorder recorderType? arg1? ... ```
To record the nodal response and response sensitivity, the most commonly used format is:
```tcl recorder Node -file disp29.out -time -node 29 -dof 1 <-precision 16 > disp ```

recorder Node -file ddm29G1.out -time -node 29 -dof 1 "sensitivity 1"

recorder Node -file ddm29G1.out -time -node 29 -dof 1 "velSensitivity 1"

```tcl recorder Node -file ddm29G1.out -time -node 29 -dof 1 "accSensitivity 1" ```
The above ‘recorder’ commands (extended for recording response sensitivities) save into files (with the file name defined after : the command ‘-file’) the responses and response sensitivities of the node 29 along the first degree of freedom (dof) direction. : Response quantities can be ‘disp’ (displacements), ‘vel’ (velocities) and ‘acc’ (accelerations). Response sensitivities are
denoted by a string in double quotes and containing the response quantity identifier (i.e., “sensitivity” for displacements,
“velSensitivity” for velocities and “accSensitivity” for accelerations) and the sensitivity parameter specified by the parameter : tag ( in this example the tag is 1).
The command ‘-precision’ is optional, and allows users to change the number of digits used to record into file the response
and/or response sensitivities. This command is particularly useful when the finite difference method is used to verify/validate : DDM-based FE response sensitivities, since high accuracy in the results may be needed.
The user may also get responses and response sensitivities directly using the following Tcl commands:

nodeDisp 29 1

nodeVel 29 1

nodeAccel 29 1

sensNodeDisp 29 1 2

sensNodeVel 29 1 2

```tcl sensNodeAccel 29 1 2 ```
These commands return the responses of the node 29 along the first dof, and their response sensitivities with respect to the
parameter with tag 2