notebox

Bash Construct List of Sub-Commands

A bash script can have subcommands, like many cli tool have.

git clone git@github.com/deyloop/notebox

clone is a subcommand of the git cli.

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1. Follow a special character delimited naming convention for Bash functions that represent a subcommand. For example, they can follow the x.subcommandA.

   That is, starting sub command function names with an x, followed by a . and then the subcommand name, subcommandA in the above example

2. Use the following code to gather a list of all sub-commands dynamically:

    # Obtain all subcommands
    while IFS= read -r line; do
      [[ $line =~ ^declare\ -f\ x\. ]] || continue 
      COMMANDS+=( "${line##declare -f x.}" )
    done < <(declare -F)
    mapfile -t COMMANDS < <(LC_COLLATE=C sort < <(printf "%s\n" "${COMMANDS[@]}"))
   

   Explanation:

   • declare -F will produce a newline delimited list of all Bash functions declared.
   • Functions that do not follow the naming convention specified above are ignored.
   • The functions that do follow the convention are added to COMMANDS
   • The function names are sorted and put into COMMANDS

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Related:

• 20220113084600 Programmable Tab Completion in Bash
• 20220113092454 Tab Completion for Bash Script Sub-Commands

Reference:

• man bash
• @rwxrob’s Bash Command Template: https://github.com/rwxrob/template-bash-command

Tags:

#literature-note #snippet #scripting #tip

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