Command Line Interface Syntax¶

The interactive CLI is provided by the milk-cli executable (typically aliased as milk). Source code is in src/cli/CLIcore/.

[!NOTE] Standalone executables (milk-fpsexec-*) have their own command-line interfaces. See FPS Standalone Modes.

See also: FPS · Streams · FAQ · Build Tiers

1. Command Line Options¶

When launching milk-cli, the following arguments are available:

Option	Description
`-h`, `--help`	Print help and exit
`-i`, `--info`	Print version, settings, info and exit
`-j`, `--journal`	Write all commands to `milk_cmdlog.txt`
`--verbose`	Be verbose
`-d`, `--debug=LEVEL`	Set debug level at startup
`-o`, `--overwrite`	Auto-overwrite FITS files (use with caution)
`-l`	Write image list to `imlist.txt`
`-m`, `--mmon=TTY`	Open memory monitor on tty device
`-n`, `--pname=NAME`	Rename process
`-p`, `--priority=PR`	Set RT priority (0–99, higher = higher)
`-f`, `--fifo=FIFO`	Specify fifo name
`-s`, `--startup=FILE`	Execute script on startup (requires `-f`)

Examples:

$ milk-cli -m /dev/tty2       # memory monitor
$ milk-cli -p 90              # high priority
$ milk-cli -f /tmp/fifo24     # custom fifo

2. Syntax Rules and Parser¶

Spaces separate arguments (count doesn't matter)
Comments follow #
Unrecognized input is interpreted as arithmetic

milk-cli > <command> <arg1> <arg2>   # comment

3. Tab Completion¶

First argument: matches command → image → filename
Additional arguments: context-aware based on command's parameter types:
FILENAME / FITSFILENAME args → filesystem paths
FPSNAME args → scan /dev/shm/fps.*.shm entries
Other args → match image stream names
Fuzzy (substring) matching automatically kicks in when prefix matching finds nothing

milk-cli > mem.<TAB>           # list commands starting with mem.
milk-cli > iofits.loadfits my<TAB>    # complete filename starting with my

4. Ghost Suggestions¶

As you type, a dim "ghost" suggestion appears inline based on your command history. Press the right arrow key to accept it.

5. Argument Hints¶

When a known command is typed, the bottom line shows the command's syntax with <angle bracket> parameter tokens. The active argument position is highlighted in bold cyan, advancing as you type each argument.

6. Readline Editing¶

GNU readline is used for line editing. Type helprl at the prompt for a quick reference. See GNU readline documentation.

Key bindings include Ctrl+A (start of line), Ctrl+E (end of line), Ctrl+R (reverse history search), and arrow keys for navigation.

The CLI also reads commands from cmdfile.txt if it exists, executing them top-to-bottom and removing each line as it is read.

7. Help Commands¶

milk-cli > ?                       # print help
milk-cli > help                    # same as ?
milk-cli > helprl                  # readline quick reference
milk-cli > lm?                     # list all loaded modules
milk-cli > m? <module>             # list commands for a module
milk-cli > m?                      # list commands for all modules
milk-cli > cmd? <command>          # detailed command description
milk-cli > cmd?                    # describe all commands
milk-cli > cmdinfo? <pattern>      # search command info by regex

Command names and descriptions are color-coded: cyan for command names, green for descriptions, yellow for examples, dim for source file paths.

8. Important Commands¶

milk-cli > ci                      # compilation info & memory usage
milk-cli > mem.listim                  # list all images in memory
milk-cli > listimf <file>          # list images, write to file
milk-cli > !<syscmd>               # execute system command
milk-cli > quit                    # exit (or: exit, exitCLI)
milk-cli > mem.mk2Dim <im> <xs> <ys>   # create 2D image
milk-cli > usleep <usec>           # sleep for <usec> microseconds
milk-cli > dpsingle                # set default precision to float
milk-cli > dpdouble                # set default precision to double
milk-cli > cd <dir>                # change current working directory
milk-cli > pwd                     # print current working directory

9. FITS File I/O¶

FITSIO is used for FITS file I/O. Requires USE_CFITSIO=ON. See Build Tiers.

milk-cli > iofits.loadfits im1.fits imf1       # load as "imf1"
milk-cli > iofits.loadfits im1.fits            # auto-name from filename
milk-cli > iofits.loadfits im1.fits.gz im1     # load compressed FITS
milk-cli > iofits.save_fl im1 imf1.fits        # save as float
milk-cli > iofits.save_fl im1 "!im1.fits"      # overwrite existing file

10. Persistent History¶

Command history is saved to ~/.milk_history and loaded at startup. Up to 1000 entries are retained between sessions.

milk-cli > history              # show last 20 commands
milk-cli > history 50           # show last 50 commands

Use Ctrl+R for interactive reverse search through history.

11. History Expansion¶

Shortcut	Description
`!!`	Re-run the last command
`!! args`	Append `args` to the last command
`!$`	Insert the last argument of the previous command
`!prefix`	Re-run the last command starting with `prefix`

The expanded command is printed with a >> prefix before execution.

milk-cli > iofits.loadfits im1.fits im1
milk-cli > !!                   # re-runs: iofits.loadfits im1.fits im1
milk-cli > iofits.save_fl !$    # expands to: iofits.save_fl im1

12. Fuzzy History Search¶

milk-cli > searchhist mem.listim

Finds all history entries containing "mem.listim" (case- insensitive) and highlights the matching substring in yellow. Shows match count at the end.

13. Startup Script¶

Commands in ~/.milkrc are executed line-by-line on startup. Blank lines and # comments are skipped.

# Example ~/.milkrc
alias li mem.listim
synhl on

14. Script Execution¶

milk-cli > source myscript.milk  # run commands from file

Blank lines and # comments are skipped. On error, the filename and line number are printed in red.

Example myscript.milk:

# This is a sample milk script
!echo "Starting image processing..."

# Create a 100x100 image named 'myimg'
mem.mk2Dim myimg 100 100

# Perform some basic arithmetic
im1=myimg+5.0

# Save to FITS using an environment variable
iofits.saveFITS im1 ${HOME}/im1_test.fits

# Print current images in memory
mem.listim

15. Command Timing¶

milk-cli > time mem.listim      # measure execution time

Prints the elapsed wall-clock time after the command completes.

16. Command Chaining¶

Sequential, conditional, and unconditional chaining:

milk-cli > cmd1 ; cmd2         # always run cmd2 after cmd1
milk-cli > cmd1 && cmd2        # run cmd2 only if cmd1 succeeds
milk-cli > cmd1 || cmd2        # run cmd2 only if cmd1 fails

Operators inside double-quoted strings are not treated as chain separators.

17. Pipe to Shell¶

Pipe a CLI command's output to a standard shell command:

milk-cli > mem.listim | grep wfs     # filter image list
milk-cli > cmd? | head -5            # show first 5 help lines

18. Output Redirect¶

Redirect command output to a file:

milk-cli > mem.listim > imlist.txt  # write image list to file

19. Environment Variable Expansion¶

$VAR and ${VAR} are expanded before execution:

milk-cli > iofits.loadfits ${HOME}/data/im.fits im1
milk-cli > iofits.saveFITS im1 $OUTDIR/result.fits

20. Command Substitution¶

Replace $(cmd) or `cmd` in the command line with the standard output of the command execution.

milk-cli > cd $(echo /tmp)
milk-cli > iofits.loadfits `findim.sh` result

21. Wildcard Expansion (Globbing)¶

File path wildcards like *, ?, and [] are automatically expanded into matching files if placed unquoted in arguments.

milk-cli > iofits.imgs2cube *.fits cube.fits

22. Backslash Line Continuation¶

End a line with \ to continue on the next line. The prompt changes to > for continuation lines:

milk-cli > arith.imfunc \
>   im1 im2 outim

21. Syntax Highlighting¶

The first word is colored green (valid command) or red (unknown). Toggle with:

milk-cli > synhl off             # disable
milk-cli > synhl on              # enable (default)

[!TIP] If you encounter rendering issues with syntax highlighting, disable it with synhl off.

22. Auto-Correction¶

When a command is not found, the CLI suggests the closest match using Levenshtein distance:

milk-cli > mem.lisim
Command 'mem.lisim' not found. Did you mean 'mem.listim'?

23. Command Statistics¶

milk-cli > cmdstats              # top 20 most-used commands

Shows command name and call count for the current session.

24. Configurable Prompt¶

Customize the prompt format using setprompt:

milk-cli > setprompt "%u@%h %d > "
user@host src >

Token	Expands to
`%h`	hostname
`%u`	username
`%d`	current directory basename
`%t`	HH:MM:SS
`%n`	process name

25. Command Aliases¶

milk-cli > alias li mem.listim   # create alias
milk-cli > unalias li            # remove alias
milk-cli > aliases               # list all aliases

Aliases persist in ~/.milk_aliases.

26. Command Bookmarks¶

Save and recall multi-command sequences:

milk-cli > bookmark save setup "cmd1 ; cmd2 ; cmd3"
milk-cli > bookmark run setup
milk-cli > bookmark list
milk-cli > bookmark rm setup

Bookmarks persist in ~/.milk_bookmarks.

27. Session Logging¶

Log all executed commands with timestamps:

milk-cli > sessionlog on          # log to ~/.milk_session.log
milk-cli > sessionlog mylog.txt   # log to custom file
milk-cli > sessionlog off         # stop logging

Each entry includes a timestamp and elapsed time since the session started.

28. Watch Command¶

milk-cli > watch 1000 mem.listim   # repeat every 1000ms

Press any key to stop the repeating execution.

29. Arithmetic Operations¶

Expressions not matching any command are evaluated as image arithmetic:

milk-cli > im1=sqrt(im+2.0)       # arithmetic on images

30. Module Loading¶

Load shared library modules at runtime:

milk-cli > soload mylib.so         # load shared object
milk-cli > mload COREMOD_arith     # load module by name

31. Integration with Standard Linux Tools¶

Using `cmdfile.txt` to drive milk-cli¶

milk-cli executes commands from cmdfile.txt if the file exists. This enables scripting from both inside and outside the CLI.

From inside milk-cli:

milk-cli > !ls im*.fits | xargs -I {} echo iofits.loadfits {} > cmdfile.txt

From a separate shell (while milk-cli is running):

$ ls im*.fits | xargs -I {} echo iofits.loadfits {} > cmdfile.txt

Using `imlist.txt` and `cmdfile.txt`¶

Start milk-cli with -l to maintain imlist.txt. Then filter and act on the list:

milk-cli > !awk '{if ($4>200) print $2}' imlist.txt \
        | xargs -I {} echo iofits.save_fl {} {}_tmp.fits > cmdfile.txt

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