How to read user input from an interactive text editor in Tcl

tcl-prompt-for-editor-input.sh

#!/usr/bin/env tclsh
#
# How to read user input from an interactive text editor in Tcl
# =============================================================
#
# Permission to use, copy, modify, and/or distribute this software for any
# purpose with or without fee is hereby granted.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
# REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
# AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
# INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
# LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
# OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
# PERFORMANCE OF THIS SOFTWARE.
#

# Editor to use, set to vi if not specifed in the environment
# -----------------------------------------------------------

if {[info exists ::env(EDITOR)]} {
    set editor $::env(EDITOR)
} else {
    set editor "vi"
}

# Create a temporary input file
# -----------------------------
file tempfile temp_file

# Open the input file for editing
# -------------------------------
exec $editor $temp_file <@ stdin >@ stdout 2>@ stderr

# Read the file into a variable
# -----------------------------
set opened_temp_file [open $temp_file r]
set user_input       [read $opened_temp_file]

# Cleanup
# -------
close $opened_temp_file
file delete $temp_file

# Use the input
# -------------
puts -nonewline $user_input