Houdini 20.0 Reference Stand-alone utilities


Shell utility for navigating the UNIX filesystem.

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If you are using a unix shell, spy is a fast text-based file-navigation utility for organizing your files. It provides greater speed in manipulating files than a GUI, while also providing direct access to scripts and unix commands, and being easier to use than the unix C shell.

spy runs in a window shell, and provides an efficient interface to the unix file system via its single-keystroke commands. Anything you can normally do in a c-shell, you can do in spy, but more quickly. Using single keystroke commands, spy quickly navigates between directories, and selects files in order to perform actions on them. Once files are selected, you can use all the standard unix commands with them through the use of a unix meta-key.

The most commonly used single-keystroke commands are listed in the quick reference. These commands are covered in greater detail in the following pages.

Working with files

Within a directory, you can tag a number of files to operate on. Common operations include deleting files, and displaying images on the screen. The files that are tagged will have a + to the left of the name. This section describes how to tag and untag files. Later you will see how you can use the % character in unix commands as a shorthand notation for the tagged files.

Selecting files

T Toggles the tag on the current file on/off. The second line of the spy window shows the number of selected file in brackets:

john@pisa: /n/berne/Documentation/Images/ Page 2/2 (+9) 

⌃ Ctrl + T Tags or untags all files in the current directory.

⇧ Shift + T Prompts you with a file name pattern used to toggle the tags on the files which match the pattern:

g* Enter

tags all files starting with the letter g

*.pic Enter

tags all files names ending with .pic

??.pic Enter

tags all files starting with any two characters and ending with .pic, such as 21.pic but not 121.pic.

Copying, moving, and removing

C Copies the tagged files to a new name or a new directory. When invoked, it asks you for place to copy the selected file to. If you specify a unix directory path, it will copy the file there. If a filename is entered (i.e. you didn’t have any / characters in what you typed), then the copy is named to whatever you entered.

M Moves the tagged files to a new name or a new directory. When invoked, it asks you for place to move the selected file to. If you specify a unix directory path, it will move the file there. If a filename is entered, the file is renamed.

⇧ Shift + R Removes the tagged files after prompting you for a confirmation. To delete all the contents of a directory, use the unix command: rm.

Copy buffer

There is a directory in your home directory called spy.take. It is used to store copies of files which you later put elsewhere. It is known as the copy buffer.

Y Copies ( y stands for the archaic term “yank”) tagged files into the copy buffer (spy.take). You can copy as many files, on as many occasions as you want into the copy buffer. Files in the copy buffer remain there, even between sessions.

P Pastes all the files from the copy buffer into the current directory, and empties the copy buffer.

I Displays an Inventory of files currently in the copy buffer.

Z Empties the copy buffer ).


A useful trick is to use the XWsh pop-up menu of the spy window (click in the window with RMB) to clone your current window. You can then Copy your files from the first window, and then Paste them into the directory displayed in the second window.

Creating Directories

mkdir directoryName Makes a new directory with the given name. You can put several names separated by spaces on the same line. For example:

Fmkdir myDirectory anotherDirectory R

You can delete the directories with the same spy command (S r) that you use to remove files. You will need to ensure that you have deleted all files from the directory before you do this. You can also use the unix command rm with the -r option.

Showing details

Sl Lists all tagged files. If none are tagged, this command lists information for the current file. The list shows detailed information about the files.

-rwxrw-r-- john prisms 265535 12:29 Mar 21 96 testFile

The permissions of a file are displayed in the first ten characters.

The first character tells you if it is a file, directory, or symbolic link. Then come three sets of three characters. These show the Read/Write/Executable (rwx) permissions of the file for the owner, the group to which the file belongs, and for all other users.

If a person or group has permissions to read a file, they will be able to open, read, and make copies of the file. If a person or group has permissions to write to a file, they can also modify and delete the file. If they if have permissions to execute a file, and it is an application that can be run, they will be able to run the application. If it is a directory, they will be able to go into it.

After the first ten characters, the following information is displayed:

  • The name of the owner of the file (the person who created it).

  • The name of the group to which the file belongs.

  • The size of the file in bytes.

  • The time and date on which it was last modified.

  • The name of the file itself.

If the file is a symbolic link, in place of the name of the file, it will show the pathname of the file or directory to which the link points.

F prints the type or contents of the file, such as: ascii, binary, etc.

⌃ Ctrl + W makes the currently highlighted file writable. You can only do this if you have owner or group permissions to write (make changes) to the file.

⌃ Ctrl + X makes the currently highlighted file executable. You can only do this if you have owner or group permissions to write (make changes) to the file.

Viewing file contents

If the current file is not a directory, typing D displays the contents of a text file using less.

When less displays a file, you can use the following single-key commands, which are similar to spy and vi:

J or Enter Scroll down one line.

K Scroll up one line.

F or Space Scroll forward one page.

B Scroll backward one page.

⇧ Shift + G Goes to the end of the file.

1 G Goes to the beginning of the file ( Line# then G goes to that line).

/ string Search for string in the file, and display that line.

N Go to next occurrence of string.

H Display help, including the commands listed here.

Q Enter Quit less and return to spy or unix

E or V Edit the current file using vi. If you do not know how to use vi, you can get out of it by typing O Q F R.


Once you are done editing in vi (i.e. you exited vi with the OwqR command) you are returned to less, which still displays the file. If you want to get back to spy, you will still need to quit less by typing Q Enter.

Running UNIX commands

Although many things can be done from within spy, starting Houdini or other programs is often done with unix commands.

While you are in spy, any time you need to execute a unix command, simply precede the command with the ! key, and then type the command. For example:

! df -k Enter

displays the amount of free disk space in kilobytes.

Unix commands often require the name of a file(s) as arguments. We can provide these filenames from spy by using the % character within our unix command. Anywhere this character is found, it will insert the name(s) of the currently tagged files.

For example, if the files 1.pic, 2.pic and 3.pic are tagged, then the command:

! iplay % Enter

translates into:

! iplay 1.pic 2.pic 3.pic Enter


If no file(s) are tagged, a command using the % character will act on the currently highlighted file only.

Quick reference

J or K

Move cursor down / up

H or L

Move cursor left / right


Up a directory


Down a directory or Display a file (view only) using less

Q + Enter

Quit less (if you entered file with D )

E or V

Both of these will Edit a file (with vi) or Enter directory

⌃ Ctrl + B or ⌃ Ctrl + F

Back or Forward a page


Tag file (on/off toggle)

⇧ Shift + T

Pattern tag (enter string to select all files that match)

⌃ Ctrl + T

Tag all files in directory (on/off toggle)


Copy (yank) file(s) to the copy buffer


Inventory of files in the copy buffer


Paste a file from the copy buffer (and clears the buffer)


Clear the copy buffer

⇧ Shift + R

Remove (delete) tagged files or current file if none tagged


Copy highlighted or tagged files to user specified directory


Move tagged files to a new Name or Directory

⇧ Shift + J

Jump to user specified directory

⇧ Shift + H

Jump to Home Directory

⇧ Shift + L

File info (on highlighted or tagged files)

⌃ Ctrl + L

Redraw the screen


Enter unix command (use % to refer to tagged files)

/ string

Search (move to) file whose name begins with string

Command history

! cmd Enter executes cmd.

For example:

!df Enter

displays the amount of free disk space.

!! Enter Re-executes the last unix command.

!! string Enter Re-executes the last command which started with the string string. For example, if a recent command was:

!hview test.pic Enter

then the command

!!im Enter

…re-executes it.

!? Displays the command history - a list of the most recent unix commands you've executed. As in the jump history, you can move down and up the list with J and K. Movement forward and backward along one line is accomplished with the Space and ⌫ Backspace keys.

Once the list of command history is displayed, you can edit the line with the following commands, similar to the vi editor:

Enter Typing the Enter key executes the current command as-is.

/ string Enter Moves the cursor to the next command starting with string.

A Adds text after the location of the cursor until you type E or Enter.

I Inserts text before the location of the cursor until you type the E or Enter key.

X Deletes the character in front of the cursor.

⇧ Shift + C Replaces text after the cursor with text you enter, until you type E or Enter.

D + W Deletes the current word.

C + W Replaces current word with text you enter until you type the E or Enter keys.

⌃ Ctrl + C You can abort the jump at any time by pressing ⌃ Ctrl + C or ⌦ Del depending on your setup.

! E Displays the most recent command and allows the above editing commands to be used. Then, when you press Enter, the command is executed. As above, ⌃ Ctrl + C or ⌦ Del aborts the command.

Additional commands

? Lists all single keystroke commands, as described in this chapter.

⌃ Ctrl + L Redraws the screen if it has been corrupted by other programs sending text to the same window shell. If you are ever unsure that what you see in the spy window is correct information, this command ensures that it is up-to-date.

⌃ Ctrl + P Lists the processes you are running. You can use the unix kill command to kill these processes.

⇧ Shift + Q Quits spy and leaves the jump history and the command history in the file .spyHistory file your home directory.

spy is set up with several default key mappings:

1 Equivalent to: hview % Enter (where % is the highlighted file)

2 Equivalent to: houdini % Enter

3 Show cpu system activity.

4 Show most active cpu process.

⇧ Shift + M Read mail using current mail program.


A .spyrc file in your home directory allows you to customize spy with a list of key-mappings. Each entry assigns a commonly used command to a single keystroke. For example, the default .spyrc file assigns hview to the 1 key, and launch Houdini is assigned to the 2 key.

Edit the .spyrc file with a text editor (such as vi) to add your own commonly used commands. Do this with the map command. For example:

map 9 unix jot %

Open selected file with jot when you type the 9 key.

map 8 jump =$HFS

Jump to directory held by variable $HD.

map > jump :?

Show jump history.

map ? unix_cmd :?

Show unix command history.

Be sure to map only those keys which spy does not already use, or you will have trouble executing certain spy commands.

Use ⌃ Ctrl + R to reload the .spyrc file after you have saved your changes.


Keywords (such as jump, unix_cmd) must be in lowercase, and must have a space after them.


Stops the Press Enter to Continue messages from appearing. It also lets the spy “Continue:” prompt accept any spy command immediately after the previous command finishes without having to type Enter first.


Spy will find patterns in the middle of filenames as well as at the beginning of the filenames. For example, if you search for “12” and the directory contains:

123.rc flame123.pic flame212.pic

then each of these files would be found in turn.

Without relaxsearch, you would have to search for *12 to get the same behavior.

If you set the relaxsearch mode and want to find only filenames beginning with 12 then search for ^12. This works because the leading '^' is a standard search pattern character meaning “the beginning of a line”.


You can customize the display of the file listings such that files are displayed in different colors. This only works if the terminal you are running spy from is an ansi terminal. To check if your terminal is an ansi terminal, use the following unix command:

echo $TERM

To customize display of colors with your .spyrc file, use this command:

color filenamePattern color

where filenamePattern is the string to match (you can use standard *, [] and ? as wild-card characters), and color is one of the colors in the list below.

For filenamePattern , you can also specify certain file types: -dir for directory, -x for executable, -tagged for selected files.

The color parameter must be one of

  • white reverse_white

  • red reverse_red

  • yellow reverse_yellow

  • green reverse_green

  • cyan reverse_cyan

  • blue reverse_blue

  • purple reverse_purple

  • black reverse_black

If you added something like:

color *.hip purple
color -dir yellow
color core reverse_red
color -tagged reverse_blue
color -x green

to your .spyrc file, it would color all .hip files purple, all directories yellow; all “core” files in reverse red; all tagged (selected) files in blue; and all executable files (as in unix permissions) green.


Toggles the display of color. You can map this to another key, such as uppercase “C”, in your .spyrc file by using:

map C colortoggle 

in your .spyrc file. The ⇧ Shift + C key combination is the default for turning the display of color on and off.


Sometimes it is desirable to exclude the display of certain file types. This can be accomplished using ignore masks. To set up an ignore mask, use the .spyrc command ignoremask. The syntax for this command is:

ignoremask [mask] [group] 

The mask is a pattern string which follows the same rules that spy uses when searching for files within a directory. The group number is optional. If no group number is specified, group 0 is used.

Here is an example of an ignore mask that tells spy not to display all files starting with a period ( “ . ” ).

ignoremask .* 

A maximum of 256 ignore masks can be specified in the .spyrc file. Each ignore mask command only accepts a single mask string. However, masks can be accumulated by using the same group number. For example:

ignoremask Makedepend 1 ignoremask *.o 1 

This means that when group 1 is in use, all files matching the patterns *.o and Makedepend will not be shown. spy has a limit of 64 groups numbered from 0 to 63.


Toggles the use of the ignore groups. The syntax for this command is:

ignoretoggle [group] 

It is possible to map a key to toggle the display of a particular group by adding the following to the .spyrc file.

map [key] ignoretoggle =[group] 

Here is an example which maps the O key to toggle the display of all .o files in a directory:

ignoremask *.o 1 
map o ignoretoggle =1


Whether a group will be in use on starting spy.

ignoredefault [group] [use] 

If this command is not present in the .spyrc file, all groups will be used. The use parameter should be set to 0 if this group should not be used on startup and 1 otherwise.

In general, you should never need to remap the spy key functions, but if for some reason you would like to, you can use the map command to reassign the keys spy uses with the following list of Key Functions.

For example, if you were using a Dvorak keyboard layout, but wanted to maintain the six directory navigation keys in the same physical location, you could add the following mappings to your .spyrc file:

map d left
map h down
map t up
map n right
map g climb
map e display

The following special key names are available:

  • <left>

  • <right>

  • <up>

  • <down>

  • <s-left> (⇧ Shift + )

  • <s-right> (⇧ Shift + )

  • <home>

  • <end>

  • <pagedown>

  • <pageup>

  • <insert>

  • <f1..f12>

To get spy to use the arrow keys instead of J K H L, add this into your .spyrc:

map <left>   left
map <right>  right
map <up>     up
map <down>   down
map <enter>  display
map <s-left> climb

You can bind the following commands to keys:


Move to parent directory


toggles the display of color


Execute spy command


Copy file(s)


Show current date and time


Show file or enter directory


Move cursor down


Drop taken file(s) (Paste)


Empty taken files(s)


Edit file or enter directory


Toggle user experience


Determine type of file(s)


Shows Help. List commands mapped in .spyrc


Toggle help directory


Go to home directory


default mask to use


Set mask for filename patterns to ignore


Toggle ignore mask group


Undefined key


List taken file(s) (show Clipboard)


Jump to file or directory


List key assignments


Move cursor left


Re-load .spyrc file


Long listing of file(s)


Move file(s)


Repeat previous name search


Move cursor to next file


Go to next page


Go to previous page


Select (pick) files by pattern match


Select (pick) or unselect file (toggle)


Move cursor to previous file


Exit spy


Re-draw the screen


Remove selected file(s)


Move cursor right


Search directory for name


Add a new Environment variable


Toggle directory detail


Show memory usage


Start another shell


Take file(s) (Copy)


Execute unix command


Turn all selection (pick) flags off


Move cursor up


Display spy Version Number


Toggle visibility


Lists users that are currently logged in

Stand-alone utilities

  • abcconvert

    Convert between Alembic formats.

  • abcecho

    Print information about an Alembic file.

  • abcinfo

    Print information about an Alembic file.

  • chchan

    Copies channel collection to/from action channel format.

  • chcp

    Copies channel collection file to another format.

  • chinfo

    Prints information about a channel collection file.

  • claudio

    Copies CHOP data (clip) to/from audio formats.

  • clchan

    Copies CHOP data (clip) to/from action channel format.

  • clchn

    Copies CHOP data (clip) to/from channel collection format.

  • clcp

    Copies CHOP data (clip) to another format.

  • clinfo

    Prints information about a CHOP data (clip) file.

  • dsmconvert

  • dsmmerge

  • dsparse

    Parses and displays dialog scripts.

  • gabc

    Convert between Alembic and Houdini geometry.

  • gconvert

    Convert between Houdini polygon formats.

  • gdxf

    Converts DXF polygons to/from Houdini format.

  • geodiff

    Display Geometry Differences.

  • geps

    Converts EPS files to Houdini polygon format.

  • giges

  • ginfo

    Prints polygon file statistics.

  • glightwave

    Converts LightWave files to/from Houdini format.

  • gpdb

    Converts .pdb files to/from Houdini format.

  • gplay

    Geometry viewer.

  • gply

    Converts .ply files to/from Houdini format.

  • gptex

    Makes a ptexture image file from a geometry file.

  • greduce

    Reduces polygons in a file.

  • gwavefront

    Converts .obj files to/from Houdini format.

  • hcollapse

    Collapses a directory structure.

  • hcpio

  • hexpand

    Expands hip files into a directory structure.

  • hkey / License Administrator

    Opens a graphical user interface for viewing and managing licenses and license server options.

  • hoiiotool

    Swiss-army knife of image operation tools.

  • hotl utility

    Command line utility to work with .hda/.otl files.

  • hrender

  • hsc

  • hscript

    Command line HScript interpreter.

  • hserver

    Houdini communicates through this proxy server to the sesinetd licensing daemon.

  • htexcache

    Query or modify the disk texture cache.

  • husk

    Command line utility for rendering a USD file using Karma or some other Hydra client.

  • i3dconvert

  • iautocrop

    Crops images based on pixel values.

  • icineon

    Convert images from 10-bit Cineon format to an 8 bit format.

  • icomposite

  • iconvert

    Converts an image of one type to another type.

  • icp

    Isolate a region of an image in a new image.

  • idenoise

    Removes noise from an image file.

  • idiff

    Display Image Differences.

  • iflip - Flip Image

  • iinfo

    Outputs information about an image.

  • ilut

    Generates a lookup table (LUT) from standard channel formats or another LUT.

  • ilutcomp

    Generates a single lookup table (LUT) from from two LUTs.

  • ilutinfo

    Prints information about a lookup table (LUT) file.

  • imaketx

    Creates mipmapped .exr or .rat textures from image files.

  • imdisplay

    Sends an image to an mdisplay window.

  • iprint

    Prints the RGBA values for an image as text.

  • iquantize

    Reduces the number of colors in an image.

  • isixpack

    Generates an environment/reflection map from six images representing the six sides of a cube, or a cross image.

  • itilestitch

    Assemble a series of image files with crop windows into a single image.

  • izg

    Converts Z-depth images to 8-bit grayscale images.

  • Launcher

    The Houdini Launcher downloads, installs, upgrades, and uninstall Houdini and its components.

  • mcacclaim

    Converts an Acclaim motion file to a Houdini script and channel file(s).

  • mcbiovision

    Converts a BioVision motion file to a Houdini script and channel file(s).

  • mcmotanal

    Converts a Motion Analysis TRC motion file to a Houdini script and channel file(s).

  • mcp

    Convert an image sequence to a movie file.

  • minfo

    Prints information about movie files.

  • mqserver

    Message Queue Server for PDG/TOPs

  • py23convert

    Convert Python 2 expressions in HDAs to Python 2/3.

  • renderstatsoverlay

    Generates a (possibly scaled down) version of a rendered image with render statistics baked in.

  • renderstatsreport

    Generates an HTML page containing render statistics from an EXR image.

  • sesictrl

    Sets Houdini license server options from the command line.

  • sesinetd

    The Houdini license server. This program runs in the background managing Houdini licenses.

  • siminfo

    Prints simulation cache file statistics.

  • spiff

    Display Text Differences.

  • spy

    Shell utility for navigating the UNIX filesystem.

  • usdview

    Command line utility for viewing and inspecting USD scenes.

  • vexcache

    Query or modify the VEX compile cache.

  • vexexec

    Execute a cvex shader.