Parameters and Environment Variables

Table of Contents

Command Line Parameters:
#

Parameters are accessed through the argv list.

Script Parameters

1lumesh script.lm Alice tom
2# in script.lm
3print argv  # Outputs "[Alice, tom]"
4print argv[0]  # Outputs "Alice"

Command Line Passing

1lume -c 'print argv' -- a b   # or
2lume -c 'print argv' a b
3# Outputs
4[a, b]

Environment Variables
#

System Environment Variables
#

Sys.env() lists system environment variables.

1set var value    # Set a system environment variable
2unset var        # Remove a system environment variable

Typical system variables:

1PATH             # System environment variable
2HOME             # System environment variable

Current Environment Variables
#

Sys.vars() lists current environment variables.

1let var value    # Set a current environment variable
2del var          # Remove a current environment variable

Lumesh-defined current environment variables:

1env              # Lists all current environment variables
2IS_LOGIN         # Whether it is a LOGIN-SHELL
3IS_INTERACTIVE   # Whether it is in interactive mode
4IS_STRICT        # Whether it is in strict mode

IFS
#

This is a special environment variable used for internal field separation.

IFS functionality controls three states of behavior:

Mask	Syntax Type	Mask Functionality Not Enabled	Enabled but IFS Value Not Set	Enabled and IFS Value Set
2	Command String Parameters	Pass the entire string as a single parameter	Use `newline` as the default separator	Split using IFS value as the separator
4	For Loop/Loop Dispatch Pipe Split	Attempt to split by `line, space, semicolon, comma` in order	Attempt to split by `line, space, semicolon, comma` in order	Split string using IFS value
8	String.split Function	Split using `whitespace` (`split_whitespace`)	Use `space(" ")` as the default separator	Split using IFS value as the separator
16	From.csv/Into.csv Functions	Use `comma(",")` as the CSV separator	Use `comma(",")` as the default separator	Use the first character of IFS value as the CSV separator*
32	Ui.pick Function	Use `newline("\n")` to separate options	Use `newline("\n")` as the default separator	Split option list using IFS value

*Note: The CSV functions have special handling; if IFS is set to "\n", it still uses a comma as the separator.

Control Logic Flow

First Level Check: Check if the LUME_IFS_MODE bitmask enables the corresponding functionality.
Second Level Check: If the functionality is enabled, check if the IFS variable is set to a valid string value.
Third Level Execution: Execute the corresponding splitting logic based on the check results.

This three-layer control design provides maximum flexibility and backward compatibility. The IFS variable will be ensured to exist during system initialization.

Configuration Description
LUME_IFS_MODE: Bitmask controlling which syntax uses IFS.
IFS: Actual separator string.
Default Value: LUME_IFS_MODE defaults to 2, affecting only command parameter splitting.
Usage Example

To enable all IFS functionalities, you can set:

1let LUME_IFS_MODE = 62  # 2+4+8+16+32 = 62, enabling all functionalities

To enable only specific combinations of functionalities, you can sum the corresponding bit values. For example:

To enable only command parameters and string splitting: LUME_IFS_MODE = 10 (2+8)
To enable for loops and CSV parsing: LUME_IFS_MODE = 20 (4+16)

IFS (Internal Field Separator) is a shell concept implemented in Lumesh as a configurable string splitting mechanism. Through a bitmask system, users can precisely control which syntax contexts use IFS splitting and which use default behavior. This design provides backward compatibility while allowing users to customize string processing behavior as needed. [1] https://developer.mozilla.org/en-US/docs/Web/CSS/Guides/Environment_variables/Using [2] https://www.reddit.com/r/learnpython/comments/gysg3z/can_somebody_explain_to_me_why_exactly/ [3] https://en.wikipedia.org/wiki/Environment_variable [4] https://www.ibm.com/docs/ssw_aix_72/osmanagement/HT_listing_env_var.html [5] https://medium.com/chingu/an-introduction-to-environment-variables-and-how-to-use-them-f602f66d15fa [6] https://www.ninjaone.com/blog/how-to-view-and-manage-environment-variables/ [7] https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html [8] https://configu.com/blog/setting-env-variables-in-windows-linux-macos-beginners-guide/ [9] https://developer.android.com/tools/variables [10] https://notes.kodekloud.com/docs/Advanced-Bash-Scripting/Special-Shell-Variables/ifs [11] https://medium.com/@linuxrootroom/understanding-ifs-in-bash-scripting-3c67a39661e9 [12] https://www.baeldung.com/linux/ifs-shell-variable [13] https://learn.microsoft.com/en-us/windows/win32/procthread/environment-variables [14] https://stackoverflow.com/questions/780188/when-to-use-environment-variable-or-command-line-parameter [15] https://unix.stackexchange.com/questions/184863/what-is-the-meaning-of-ifs-n-in-bash-scripting [16] https://docs.aws.amazon.com/cli/v1/userguide/cli-configure-envvars.html [17] https://en.wikipedia.org/wiki/Input_Field_Separators [18] https://www.shellscript.sh/examples/ifs/ [19] https://www.tutorialspoint.com/the-meaning-of-ifs-in-bash-scripting-on-linux [20] https://www.gatsbyjs.com/docs/how-to/local-development/environment-variables/ [21] https://journals.librarypublishing.arizona.edu/jslat/article/111/galley/105/view/ [22] https://mywiki.wooledge.org/IFS [23] https://stackoverflow.com/questions/26479562/what-does-ifs-do-in-this-bash-loop-cat-file-while-ifs-read-r-line-do [24] https://pubs.opengroup.org/onlinepubs/9699919799.orig/utilities/V3_chap02.html [25] https://tariqumrani.tech.blog/2023/09/04/universal-grammar/ [26] https://docs.nuance.com/speech-suite/nr-config/cfg_set_params_precedence_rules.html [27] https://docs.oracle.com/javase/tutorial/essential/environment/cmdLineArgs.html [28] https://www.geeksforgeeks.org/cpp/command-line-arguments-in-c-cpp/ [29] https://www.cherryservers.com/blog/how-to-set-list-and-manage-linux-environment-variables [30] https://superuser.com/questions/949560/how-do-i-set-system-environment-variables-in-windows-10 [31] https://www.tutorialspoint.com/cprogramming/c_command_line_arguments.htm [32] https://vercel.com/docs/environment-variables/system-environment-variables [33] https://www.computerhope.com/issues/ch000549.htm [34] https://www.whitman.edu/mathematics/java_tutorial/java/cmdLineArgs/cmdLineArgs.html [35] https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_environment_variables?view=powershell-7.5 [36] https://unix.stackexchange.com/questions/244323/how-to-show-an-environment-variables-current-value [37] https://kevinlinxc.medium.com/viewing-and-setting-environment-variables-in-every-shell-4df43127bd8 [38] https://stackoverflow.com/questions/5327495/list-all-environment-variables-from-the-command-line [39] https://superuser.com/questions/1533858/ifs-variable-in-linux [40] https://www.reddit.com/r/learnpython/comments/rvugkv/anyone_to_explain_what_command_line_arguments_are/ [41] https://learn.microsoft.com/en-us/windows/terminal/command-line-arguments [42] https://gobyexample.com/command-line-arguments [43] https://jdtournier.github.io/cmdline-tutorial/intro.html [44] https://docs.unity3d.com/6000.3/Documentation/Manual/CommandLineArguments.html