Cadence environment and setup files


The key to succesfully run the different VLSI tools is to know the most important configuration files and how the system administrator has planned them to be used. A basic knowledge about these files is fundamental in helping users to fix the most common problems by themselves. Keep in mind that with a standard VLSI account you have write privileges only inside your home directory and in the system temporary /tmp. Therefore each user should exploit as much as possible customizations which can be made inside the local area. In general keep backups of various configuration files (e.g. cp filename filename.old) each time before making changes.

and to Cadence's design tools All the examples will be referred to the Cadence IC 6.1.x (Virtuoso) platform. The full path for the referenced $IC_DIR environment variable is /usr/cadence/IC_6.1.x, corresponding to the top Cadence IC 6.1.x installation directory (the last software release is 6.1.5). Use the setenv command:

setenv IC_DIR /usr/cadence/IC_6.1.5

For detailed information about the Cadence IC general configuration please refer to the Virtuoso Software Licensing and Configuration User Guide. The relative pdf file is


A well commented set of sample files comes with the Cadence IC installation itself. Sample home directory setup files (e.g. .cshrc and .cdsinit) can be found in the $IC_DIR/tools/dfII/cdsuser directory, whereas working directory templates (e.g. .cdsenv and cds.lib) have been placed in $IC_DIR/tools/dfII/samples:

ls -l  $IC_DIR/tools/dfII/cdsuser
ls -l  $IC_DIR/tools/dfII/samples

These files can be copied to a your local area and then customized. We suggest to create in your ~/scratch directory a new directory to contain the original templates, e.g.

cd ~/scratch
mkdir sample.files

The first time you run a Cadence tools (e.g. virtuoso) a ./.cadence hidden directory is automatically created in your working directory and a further ~/.cadence is created in the home directory. These are may be used to customize the Cadence environment.

In this section we introduce the most important set of initialization files related to Cadence tools. We can distinguish between site (global) and user (local) setup files. Site initialization files are provided by the system administrator and are used to set up a common environment for the various Cadence tools and for the chosen technology. On the other hand, each user can customize the Cadence behavior to fit his needs by using local initialization files. Of course individual user settings override any global customization. We stress again that each user should exploit as much as possible local customizations.

The main Cadence initialization files are named .cdsenv and .cdsinit. Depending on the system administrator setup, user .cdsinit files may have a different name like .cdsinit_personal, .cdsinit_user or .cdsinit_local. Both .cdsenv and .cdsinit are used to define the Cadence environment, but with some differences. .cdsenv files follow their own syntax and are used to set tool options and user preferences. The .cdsinit files use SKILL syntax and typically are used just to load further SKILL setup files into the system (e.g. bindkeys files). The .cdsenv files are loaded before the .cdsinit ones. Therefore settings defined in the .cdsinit files may override settings placed in the .cdsenv. See also

.cdsenv files are loaded from different paths. Each tool has its own default .cdsenv file, placed in $IC_DIR/tools/dfII/etc/tools/<application>/ directories (e.g. $IC_DIR/tools/dfII/etc/tools/schematic/.cdsenv for Virtuoso Schematic Editor). A site .cdsenv could be put by the system administrator in the $IC_DIR/tools/dfII/local/ directory, which is the site customization directory. In general this is a modified copy of the sample IC_DIR/tools/dfII/samples/.cdsenv file which comes with the Cadence IC installation. User customizations can be defined in a local ~/.cdsenv in your home directory. When you start a Cadence session, if the CDS_LOAD_ENV environment variable is not set the program loads all the above mentioned .cdsenv files in the following sequence:

  • $IC_DIR/tools/dfII/etc/tools/<application>/.cdsenv
  • $IC_DIR/tools/dfII/local/.cdsenv (site customizations)
  • ~/.cdsenv (user customizations)

Any value defined in the home ~/.cdsenv overrides those previously loaded. Please note that the default search mechanism for the .cdsenv file does not look in the working directory. Hence a ./.cdsenv file placed in your working directory is not loaded by default. If you want it to be loaded, you have to set the CDS_LOAD_ENV environment variable equal to addCWD in your .cshrc:

setenv CDS_LOAD_ENV addCWD

Alternatively you can put a


statement in the home .cdsinit_personal described below.

A working directory ./.cdsenv is useful to define customizations related to the specific technology you are working with (e.g. model files, layout options etc). Make a local copy of the sample .cdsenv file and use this template for your ~/.cdsenv and ./.cdsenv:

cp $IC_DIR/tools/dfII/samples/.cdsenv ~/scratch/sample.files/cdsenv.sample 

Before you start customizations read the entire file and the comments. Use more cdsenv.sample or less cdsenv.sample to see the file content. User preferences can be also automatically saved to a .cdsenv file from Cadence itself, e.g. by using CIW ⇒ Options ⇒ Save defaults.

FIXME (screenshot!)

For more information about .cdsenv see also

The loading procedure is slight different for the .cdsinit files. Only the first .cdsinit file found during Cadence startup is loaded, then the search stops and no more .cdsinit files would be automatically loaded unless explicitely specified in the first one. The first file encountered is the site .cdinit provided by the system administrator and placed in the $IC_DIR/tools/dfII/local/ directory. This is a customized copy of the sample IC_DIR/tools/dfII/samples/local/cdsinit site file which comes with the Cadence IC installation. Then it's up to the site .cdsinit to load user customization files, named ~/.cdsinit_personal in the home directory and ./.cdsinit_local or ./.cdsinit in the working directory. The site .cdsinit also loads a technology-dependent initialization file named .cdsinit_tech provided by the manufacturer, which is usually placed in the main PDK installation directory. Inspect the content of the site .cdsinit, e.g.

more  $IC_DIR/tools/dfII/local/.cdsinit

and try to identify the various load statements for the above mentioned files. The overall loading sequence is the following:

  • $IC_DIR/tools/dfII/local/.cdsinit (site initialization file)
  • ~/.cdsinit_personal (user customizations)
  • ./.cdsinit_local or ./.cdsinit (user customizations)

Please note that a ~/.cdsinit would not be loaded at all, unless explicitely loaded by your ~/.cdsinit_personal. A user .cdsinit sample file comes with the Cadence installation in the $IC_DIR/tools/dfII/cdsuser/ directory. You can copy it to your local scratch area and then customize it, as suggested for the .cdsenv template:

cp $IC_DIR/tools/dfII/cdsuser/.cdsinit ~/scratch/sample.files/cdsinit.sample

Remember that settings placed in .cdsinit_personal and .cdsinit_local files may override the .cdsenv setup.

In general you can load in Cadence whatever initialization file you want, but you have to explicitely include a load() statement in the user .cdsinit_personal or .cdsinit_local files, e.g.

when(isFile("/path/to/fileName") load("/path/to/fileName") )

or simply type at the CIW command prompt


Posso specificare di non caricare nessun cds.lib at virtuoso startup with the -nocdsinit option,

virtuoso -nocdsinit

.cdsinit_tech represents the main technology initialization file loaded during Cadence startup. The default template is provided by the manufacturer and comes with the PDK installation. Further customizations can be done by the system administrator reflecting the system configuration. As mentioned above the .cdsinit_tech is explicitely loaded by the site .cdsinit file, in which you can find the following directives:

processdir = getShellEnvVar("ProcessPath")
loadi( strcat(processdir "/.cdsinit_tech") )

The hard path of the .cdsinit_tech file varies with the technology. If you want to know the exact location move to the main PDK installation directory and use the find command, e.g.

cd /path/to/PDK/installatio/directory
find ./ -name .cdsinit_tech

Usually a .cdsinit_tech file sets some default user preferences and could load further technology-related SKILL scripts or context files (SKILL code compiled into binary files). In general available context files have been encrypted by the manufacturer.

If your technology supports Mentor's Calibre verification tool for design rule checks (DRC), layout versus schematic (LVS) etc. the .cdsinit_tech should also load the main calibre.skl SKILL interface which integrates Calibre menus in Cadence. Please check if your .cdsinit_tech contains something like

load(strcat(mgc_home "/shared/pkgs/icv/tools/queryskl/calibre.skl"))

It could be useful to create a symbolic link to .cdsinit_tech in your working directory:

cd ~/scratch/<tech_dir>
ln -s /path/to/.cdsinit_tech .cdsinit_tech

Al di fuori di quello che interessa all'utente, solo per dire che esiste.

Puo' caricare anche la definizione di Cadence technology-specific custom menus which will be integrated in the Cadence graphical front-ends. (typically in the form of context files, i.e. precompiled SKILL code)

The file is a SKILL script which is executed the first time a library is opened.

Loads default technology model files and display resource file display.drf

PDK utility menus, SKILL code and context files.

cd /path/to/PDK/installation/directory
find ./ -name

Log file

lo posso specificare anche at virtuoso startup

virtuoso -log /path/to/filename

e.g. put in a logs directory created in the working directory (./),

virtuoso -log ./logs/filename.log

Le default directories in cui salvare i log sono definiti in the environment variable,

setenv ???? 

This file is used for customizing simulation runs.

cp $IC_DIR/tools/dfII/cdsuser/.simrc ~/scratch/sample.files/simrc.sample

cadence printing setup file, $IC_DIR/tools/plot/.plotinit

cp $IC_DIR/tools/plot/.plotinit ~/scratch/sample.files/plotinit.sample

The cds.lib is the libraries setup file.

The default Cadence DFII cds.lib file is $IC_DIR/tools/dfII/local/cds.lib

cd ~/scratch/<tech_dir>
touch cds.lib

If you are working with a particular technology you have to include also the technology cds.lib usually located in the PDK installation directory

# default Cadence IC cds.lib
INCLUDE $IC_DIR/tools/dfII/local/cds.lib

# technology cds.lib
INCLUDE /path/to/technology/cds.lib

# users libraries
DEFINE libName ~/scratch/<tech_dir>/lib/lbName

The Cadence Library Definition file (cds.lib) is located under your Cadence installation directory. This is your library setup file A default cds.lib file is located in


cds.lib example

# cds.lib skeleton

#    Standard Cadence libraries
INCLUDE $IC_DIR/tools/dfII/local/cds.lib

#    technology libraries
INCLUDE /path/to/technology/specific/cds.lib

#    custom libraries
DEFINE library_name /path/to/libary_name
DEFINE ....   /.../.../...

Simulation results and saved states directories

By default, all simulation data and results are stored in a ~/simulation directory automatically created in your home directory the first time you run a simulation with Cadence IC. Similarly, Cadence simulation states by default are saved in a ~/.artist_states hidden directoryautomatically created in your home directory.

To change these defaults, just use in your home ~/.cdsinit or ~/.cdsinit_personal files the following directives

envSetVal("asimenv.startup" "projectDir" 'string "/path/to/your/custom/simulation/results/directory")
envSetVal("asimenv" "saveDir" 'string "/path/to/your/custom/simulation/states/directory")

You can type these statements at the CIW command prompt as well.

See also

The display resource file defines necessary layout layers for a specific technology. A good place to store the display.drf is the working directory

all technologies have different display.drf files

cd ~/scratch/<tech_dir>
cp /path/to/technology/display.drf .

or simply create a symbolik link:

cd ~/scratch/<tech_dir>
ln -s /path/to/technology/display.drf display.drf

CIW ⇒ Tools ⇒ Display Resource Manager… and choose Merge

For more details see the Technology File and Display Resource File User Guide located in $IC_DIR/doc/techfileuser/techfileuser.pdf

Bindkeys (hotkeys) in Cadence are keyboard shortcuts (both using single keys or sequences of keys) or mouse actions (alone or in combination with one modifier keys on the keyboard, typically Shift, Tab, Alt and Ctrl) associated to some particular task or functionality. Using bindkeys allow the designer to save time avoiding search-and-click procedures, in particular during the shematic entry phase and for layouting. Cadence's tools offer predefined sets of bindkeys, whereas a technology could introduce its own bindkeys (which may ovveride some Cadence's defaults). Of course each user is free to define custom bindkeys to fit his needs.

Bindkeys are defined in SKILL (.il) files. Sample bindkeys for Virtuoso Schematic Editor and Virtuoso Layout Editor comes with the IC installation and can be found in $IC_DIR/tools/dfII/samples/local/ and $IC_DIR/tools/dfII/samples/local/ respectively. On the other hand default bindkeys are automatically loaded at Cadence startup from the $IC_DIR/share/cdssetup/dfII/bindkeys/ directory (e.g. and Actually sample files contain the same bindkeys definition as given in the loaded files. Once Cadence opens you can view currently set bindkeys through CIW ⇒ Options ⇒ Bindkeys….

If you plan to modify default bindkeys start making a local copy in your ~/scratch area of the sample files provided with the Cadence installation, e.g.

cd ~/scratch/
mkdir bindkeys
cd bindkeys
cp  $IC_DIR/tools/dfII/samples/local/        # for schematic bindkeys
cp  $IC_DIR/tools/dfII/samples/local/          # for layout bindkeys

Further sample files can be found in the $IC_DIR/tools/dfII/samples/local/ directory.

If you want to start with a 'vanilla' Cadence environment you can ensure that default bindkeys are always loaded at Cadence startup. Simply add in your home ~/.cdsinit_personal the following lines:

printf("Loading standard bindkeys. \n")

or equivalently

printf("Loading standard bindkeys. \n")
load(prependInstallPath "samples/local/")
load(prependInstallPath "samples/local/")

Custom bindkeys for a particular technology should be placed in the working directory ./.cdsinit or ./.cdsinit_local. If you would like to create your own bindkeys, you must first know the SKILL function of the command you are trying to bind. If you don't know the SKILL function you can find it looking at output log messages registered in the CIW or in CDS.log file. Only default bindkeys will be mentioned in the WorkBook.

For more information about bindkeys see also

Customization examples

The general .cdsenv syntax is like

tool   option   type   value


layout   gravityOn   boolean   nil

The same otion defined in a .cdsinit file requires the usage of a specific SKILL function,

leSetEnv("gravityOn" nil)

Simulation options

If you want to change the default directory '~/.artist_states' used to store simulation results

asimenv.startup   data   string "~/cadence/<tech_dir>/data"

To set the default simulator, e.g. as Spectre, enter the following environment variable in your .cdsenv or .cdsinit file. Syntax to set the default simulator in the .cdsenv

asimenv.startup simulator string "spectre"

Syntax to set the default simualtor in the .cdsinit

envSetVal("asimenv.startup" "simulator" 'string "spectre")

Definire il model path:

spectre.envOpts modelPath string "/path/to/model/file.scs;section"

See also

Layout options

layout snapMode string "anyAngle"


You can edit your ./.cdsint or ./.cdsinit_local and set your preferred text editor as default as follows:

editor = "/usr/bin/nedit"

See also

License check out order

Use your local .cdsenv with

license   VSELicenseCheckOutOrder   string   "XL,L"
license   VLSLicenseCheckOutOrder   string   "GXL,XL,L"
license   ADELicenseCheckOutOrder   string   "GXL,XL,L"

See also;solutionNumber=11587412 (Cadence On-line support login required)

Last update: Luca Pacher - Apr 23, 2013