Editing system files in Linux (as root) with GUI and CLI text editors #2

Question

This is the second iteration of this question

A note to start with: the first iteration of this question can be found here:
Editing system files in Linux (as root) with GUI and CLI text editors

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As stated in there:

My intention is to POSIX-ly write one generalized function for running various text editors I use for different purposes through sudoedit, i.e. editing files as root safely. Safely = for instance, if a power loss occurs during the file edit; another example could be lost SSH connection, etc.

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I come to you now with a possible final solution:

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sudoedit enhanced

# USAGE: Just source this file into your shell for instance if using Bash, then you can use these files: ~/.bashrc or ~/.bash_aliases

# Please, customize these lists to your preference before using this script!
sudoedit__cli_editor_list='nano vi'
sudoedit__gui_editor_list='gedit emacs xed subl' # VS Code has its own work-around

sudoedit_enhanced_run ()
# Generic function for text editing as root
# the proper, safe, way through `sudoedit`.
# Expected arguments:
# $1 = editor name; obviously mandatory
# $2 = wait option; to avoid this, pass an empty string ('')
# $3, ($4), ... = file(s); at least one file must be given
{
    # check the minimum number of arguments
    if [ $# -lt 3 ]; then
        printf '%b\n' "sudoedit_enhanced_run(): Low number of arguments.\\nExpected: \$1 = editor name; \$2 = wait option; \$3, (\$4), ... = file(s).\\nPassed $#: $*" >&2
        return 1
    fi

    # let's take a closer look at the first argument, the editor
    editor_name=$1

    # store an editor alias, if there is any
    editor_alias=$( alias "$editor_name" 2> /dev/null )

    # remove that alias for now
    if [ -n "$editor_alias" ]; then
        unalias "$editor_name"
    fi

    # find out if such editor exists on the system
    # and store the first two arguments to variables
    editor_path=$( command -v "$editor_name" 2> /dev/null )
    wait_option=$2

    # if that editor does not return valid path, print error and bail
    if ! [ -x "$editor_path" ]; then
        printf '%s\n' "sudoedit_enhanced_run(): This editor ('$editor_name') is not installed on this system." >&2
        return 1
    fi

    # if we got here, then both of the things are ok;
    # so let's move past the editor and its wait option to the actual files
    shift 2

    # check if all the files exist, it does not make sense to create a file this way
    for file in "$@"; do
        if ! [ -f "$file" ]; then
            printf '%s\n' "sudoedit_enhanced_run(): This file ('$file') does not exist or it is not a regular file." >&2
            return 1
        fi
    done

    # run the editor with one-time SUDO_EDITOR set-up
    SUDO_EDITOR="$editor_path $wait_option" sudoedit "$@"

    # re-define the editor alias, if there was any, afterward
    if [ -n "$editor_alias" ]; then
        eval "$editor_alias"
    fi
}

# Editor aliases generators / definitions

for cli_editor in $sudoedit__cli_editor_list; do
    alias su$cli_editor="sudoedit_enhanced_run $cli_editor ''"
done

for gui_editor in $sudoedit__gui_editor_list; do
    alias su$gui_editor="sudoedit_enhanced_run $gui_editor -w"
done

# VS Code specific workaround to work under root
alias sucode="sudo mkdir -p /root/.vscode && sudo code -w --user-data-dir=/root/.vscode"

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Already posted on GitHub, whereas I also tried hard to describe the purpose and (in spite it shall be obvious) usage including some example images on the project GitHub page.

Answer 1

Self-review

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comments

Comments are very important to future readers, they speed up the comprehension of the whole code. I think I messed up at least one comment, (others pending review):

• original:

  # let's take a closer look at the first argument, the editor
  

• suggested:

  # store the first argument, the editor name
  

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combine what can be combined

By combining simple pieces of code, we make it easier to read.

• original:

  # store an editor alias, if there is any
  editor_alias=$( alias "$editor_name" 2> /dev/null )
  
  # remove that alias for now
  if [ -n "$editor_alias" ]; then
      unalias "$editor_name"
  fi
  

• suggested:

  # store an editor alias; and if there is any, remove it for now
  if editor_alias=$( alias "$editor_name" 2> /dev/null ); then
      unalias "$editor_name"
  fi
  

---

implement code workaround into the function

My previous solution does not do any checks for code and also, by doing this we get rid of that alien alias.

• original:

  # VS Code specific workaround to work under root
  alias sucode="sudo mkdir -p /root/.vscode && sudo code -w --user-data-dir=/root/.vscode"
  

• suggested:

  # run the editor with one-time SUDO_EDITOR set-up
  if [ "$editor_name" = code ]; then
      # code specific workaround
      sudo mkdir -p /root/.vscode &&
      sudo code -w --user-data-dir=/root/.vscode "$@"
  else
      # main command generic
      SUDO_EDITOR="$editor_path $wait_option" sudoedit "$@"
  fi
  

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avoid generating editors aliases for which editor is not installed

My previous solution is generating all editor aliases, no matter if such program is installed on the system, this could have been unpleasant to users.

• original:

  for cli_editor in $sudoedit__cli_editor_list; do
      alias su$cli_editor="sudoedit_enhanced_run $cli_editor ''"
  done
  for gui_editor in $sudoedit__gui_editor_list; do
      alias su$gui_editor="sudoedit_enhanced_run $gui_editor -w"
  done
  

• suggested:

  for cli_editor in $sudoedit__cli_editor_list; do
      if command -v "$cli_editor" > /dev/null 2>&1; then
          alias su$cli_editor="sudoedit_enhanced_run $cli_editor ''"
      fi
  done
  for gui_editor in $sudoedit__gui_editor_list; do
      if command -v "$gui_editor" > /dev/null 2>&1; then
          alias su$gui_editor="sudoedit_enhanced_run $gui_editor -w"
      fi
  done
  

Answer 2

This long line:

printf '%b\n' "sudoedit_enhanced_run(): Low number of arguments.\\nExpected: \$1 = editor name; \$2 = wait option; \$3, (\$4), ... = file(s).\\nPassed $#: $*" >&2

can easily be made more tractable by separating the lines (since we have \n in the format string) and by using single quotes where we don't want expansion (avoiding the need to write \$):

# shellcheck disable=SC2016
printf '%s\n' >&2                                                               \
       'sudoedit_enhanced_run(): Low number of arguments.'                      \
       'Expected: $1 = editor name; $2 = wait option; $3, ($4), ... = file(s).' \
       "Passed $#: $*"