"do shell script" Bash fatalerror

Scripting Forums AppleScript | Mac OS X
#1

I have multiple Bash scripts that work fine from Terminal.app, but fail if run from do shell script. Can’t decide if I’m lazy (as I likely could have rewritten all of them by now) or what, but I’d prefer not to have AppleScript-specific versions of them.

I crater in this routine (though this same technique is used elsewhere) at the exec call. Can we not open file descriptors directly in do shell script’s limitations? Would a pseudoterminal fix the problem?

I’m only a little over a decade late to the party and don’t know how

Setup() {
  ## Create STDLOG (like STDOUT but dedicated to logging)
  if [[ ! -t 3 ]]; then
    exec 3>&1             # 1 is stdout, 3 is the fd to assign stdout

    if [[ ! -t 3 ]]; then
      StdlogCreationFailure
      ## NOTREACHED
    fi

    ## Create log directory if needed
    if  [[ ! -d "${LOG_DIR}" ]]; then
      CreateLogDirectory
    fi

    Log ${LOG_DEBUG} "STDLOG open"
  fi
#2

I know little about shell scripting but it looks like your script intends to make a directory, which is likely meant to be in the root directory (PWD) which likely isn’t permitted.

The tech note that apple provided long ago shows the use of redirecting standard error but none of the numbers above ‘2’. Dunno why ‘3’ wouldn’t be allowed though.

#3

it looks like your script intends to make a directory, which is likely meant to be in the root directory (PWD) which likely isn’t permitted.

Non sequitur. The shell script makes directories just fine. And the typical login setup isn’t done for you, but you can (somewhat) trivially set this up yourself using a couple environment variables (e.g., PATH, HOME, etc) when you issue the do shell script command.

The [tech note] that apple provided long ago shows the use of redirecting standard error but none of the numbers above ‘2’. Dunno why ‘3’ wouldn’t be allowed though.

Read TN2065 w/o it providing any help; it makes no mention of file descriptors at all, outside specifying how to bundle stdout and stderr which you mentioned.

Standard File Descriptors:

  • 0 [stdin]
  • 1 [stdout]
  • 2 [stderr]

Every UN*X file or socket you open gets a file descriptor (typically starting at 3 and incrementing) – using open(2)/fdopen(3) combo is the longhand equivalent of the fopen(3) call most C programmers use.

The POSIX exec(1) command is how file descriptors are opened/closed using BaSH.

Where else would one look past the tech note itself?

#4

I have multiple Bash scripts that work fine from Terminal.app, but fail if run from do shell script .

How are you invoking your script?

Bash isn’t the default shell on MacOS. Even if your account is configured to use bash, do shell script and osascript don’t care and will use zsh (the current flavor of the month).

Unless you explicitly run your script in bash, you can’t make any assumptions as to shell-specific implementations.

#5

To just get going quickly, I was double-launching. Something like:

use AppleScript version "2.5"

property name : "Football"
property scriptname : "lift_every_voice_and_sing.bash"

do shell script "bash -c " & scriptname

Then in "lift_every_voice_and_sing.bash":

#! /bin/bash
############################################################
###
### @(#)lift_every_voice_and_sing 1.0.0
###
############################################################

## Environment
# Darwin: 17.7.0 (x86_64-apple-darwin17)
# Bash: 3.2.57

## Bash options
set -o errexit
set -o nounset
#set -o xtrace
set -o pipefail

declare -i retcode=0

echo "ENV: $(env)"

export PATH=/usr/local/bin:$PATH
export HOME=/Users/$USER

## Run actual script
(cd $HOME/Projects/nfl/bin; ./blue_80_set_hut.bash)
retcode=$?

if [[ $retcode -eq 0 ]]; then
  echo "all good"
else
  echo "fubar"
fi

exit $retcode

The Bash script "blue_80_set_hut.bash" does the actual work (where the POSIX exec call is failing).

This style double-launch was done attempting to get something working quickly integrating the two languages, fixing any discrepancies here.

#6

As I can’t find enough information to fix my file descriptor problem, I may swap direction and make my AppleScript run via Bash instead.

Maybe instead use something like "applescript_runner.scpt":

---
--- @(#)applescript_runner 1.0.0
---

use AppleScript version "2.5"

property name : "AppleScript Runner"
property author : "Martin Michel"
property version : "1.0.0"

on run {scriptfile}
    tell application "AppleScript Runner"
        do script scriptfile
    end tell
end run

and have another (unprovided) AppleScript "update_scores.scpt" to update the Numbers spreadsheet.

Somewhere in "update_numbers.bash":

#! /bin/bash
############################################################
###
### @(#)update_numbers 1.0.0
###
############################################################

## Environment
# Darwin: 17.7.0 (x86_64-apple-darwin17)
# Bash: 3.2.57

## Bash options
set -o errexit
set -o nounset
#set -o xtrace
set -o pipefail

## Binaries
declare -r OSASCRIPT="osascript"
declare -ar osProvided=(
  "${OSASCRIPT}"
)

## AppleScript paths *must* be located somewhere under user's home directory
declare -r _PROJ_HOME="${HOME}/Projects/nfl"  # awful to embed this though

## Filesystem
declare -r AS_DIR="${_PROJ_HOME}/AS"

## AppleScript
declare -r applescript_runner="${AS_DIR}/applescript_runner.scpt"
declare -r numbers_applescript="${AS_DIR}/update_scores.scpt"

## Functions
UpdateScores() {
  ## Runner needed to backdoor allowing user interaction (per u/Martin_Michel)
  ${OSASCRIPT} ${applescript_runner} ${numbers_applescript}
}
...