sbang: convert sbang script to POSIX shell
`sbang` was previously a bash script but did not need to be. This
converts it to a plain old POSIX shell script and adds some options. This
also allows us to simplify sbang shebangs to `#!/bin/sh /path/to/sbang`
instead of `#!/bin/bash /path/to/sbang`.
The new script passes shellcheck (with a few exceptions noted in the file)
- [x] `SBANG_DEBUG` env var enables printing what *would* be executed
- [x] `sbang` checks whether it has been passed an option and fails gracefully
- [x] `sbang` will now fail if it can't find a second shebang line, or if
the second line happens to be sbang (avoid infinite loops)
- [x] add more rigorous tests for `sbang` behavior using `SBANG_DEBUG`
This commit is contained in:
Todd Gamblin
160
bin/sbang
160
bin/sbang
@@ -1,4 +1,4 @@
|
||||
#!/bin/bash
|
||||
#!/bin/sh
|
||||
#
|
||||
# Copyright 2013-2020 Lawrence Livermore National Security, LLC and other
|
||||
# Spack Project Developers. See the top-level COPYRIGHT file for details.
|
||||
@@ -8,32 +8,34 @@
|
||||
#
|
||||
# `sbang`: Run scripts with long shebang lines.
|
||||
#
|
||||
# Many operating systems limit the length of shebang lines, making it
|
||||
# hard to use interpreters that are deep in the directory hierarchy.
|
||||
# Many operating systems limit the length and number of possible
|
||||
# arguments in shebang lines, making it hard to use interpreters that are
|
||||
# deep in the directory hierarchy or require special arguments.
|
||||
#
|
||||
# `sbang` can run such scripts, either as a shebang interpreter, or
|
||||
# directly on the command line.
|
||||
#
|
||||
# Usage
|
||||
# -----------------------------
|
||||
# -----
|
||||
# Suppose you have a script, long-shebang.sh, like this:
|
||||
#
|
||||
# 1 #!/very/long/path/to/some/interpreter
|
||||
# 1 #!/very/long/path/to/some/interp
|
||||
# 2
|
||||
# 3 echo "success!"
|
||||
#
|
||||
# Invoking this script will result in an error on some OS's. On
|
||||
# Linux, you get this:
|
||||
#
|
||||
# $ ./long-shebang.sh
|
||||
# -bash: ./long: /very/long/path/to/some/interp: bad interpreter:
|
||||
# $ ./longshebang.sh
|
||||
# -bash: ./longshebang.sh: /very/long/path/to/some/interp: bad interpreter:
|
||||
# No such file or directory
|
||||
#
|
||||
# On Mac OS X, the system simply assumes the interpreter is the shell
|
||||
# and tries to run with it, which is likely not what you want.
|
||||
# On macOS, the system simply assumes the interpreter is the shell and
|
||||
# tries to run with it, which is not likely what you want.
|
||||
#
|
||||
#
|
||||
# `sbang` on the command line
|
||||
# -----------------------------
|
||||
# ---------------------------
|
||||
# You can use `sbang` in two ways. The first is to use it directly,
|
||||
# from the command line, like this:
|
||||
#
|
||||
@@ -42,12 +44,12 @@
|
||||
#
|
||||
#
|
||||
# `sbang` as the interpreter
|
||||
# -----------------------------
|
||||
# --------------------------
|
||||
# You can also use `sbang` *as* the interpreter for your script. Put
|
||||
# `#!/bin/bash /path/to/sbang` on line 1, and move the original
|
||||
# `#!/bin/sh /path/to/sbang` on line 1, and move the original
|
||||
# shebang to line 2 of the script:
|
||||
#
|
||||
# 1 #!/bin/bash /path/to/sbang
|
||||
# 1 #!/bin/sh /path/to/sbang
|
||||
# 2 #!/long/path/to/real/interpreter with arguments
|
||||
# 3
|
||||
# 4 echo "success!"
|
||||
@@ -56,10 +58,10 @@
|
||||
# success!
|
||||
#
|
||||
# On Linux, you could shorten line 1 to `#!/path/to/sbang`, but other
|
||||
# operating systems like Mac OS X require the interpreter to be a
|
||||
# binary, so it's best to use `sbang` as a `bash` argument.
|
||||
# Obviously, for this to work, `sbang` needs to have a short enough
|
||||
# path that *it* will run without hitting OS limits.
|
||||
# operating systems like Mac OS X require the interpreter to be a binary,
|
||||
# so it's best to use `sbang` as an argument to `/bin/sh`. Obviously, for
|
||||
# this to work, `sbang` needs to have a short enough path that *it* will
|
||||
# run without hitting OS limits.
|
||||
#
|
||||
# For Lua, node, and php scripts, the second line can't start with #!, as
|
||||
# # is not the comment character in these languages (though they all
|
||||
@@ -67,59 +69,115 @@
|
||||
# like this, using --, //, or <?php ... ?> instead of # on the second
|
||||
# line, e.g.:
|
||||
#
|
||||
# 1 #!/bin/bash /path/to/sbang
|
||||
# 1 #!/bin/sh /path/to/sbang
|
||||
# 2 --!/long/path/to/lua with arguments
|
||||
# 3 print "success!"
|
||||
#
|
||||
# 1 #!/bin/bash /path/to/sbang
|
||||
# 1 #!/bin/sh /path/to/sbang
|
||||
# 2 //!/long/path/to/node with arguments
|
||||
# 3 print "success!"
|
||||
#
|
||||
# 1 #!/bin/bash /path/to/sbang
|
||||
# 1 #!/bin/sh /path/to/sbang
|
||||
# 2 <?php #/long/path/to/php with arguments ?>
|
||||
# 3 <?php echo "success!\n"; ?>
|
||||
#
|
||||
# How it works
|
||||
# -----------------------------
|
||||
# `sbang` is a very simple bash script. It looks at the first two
|
||||
# lines of a script argument and runs the last line starting with
|
||||
# `#!`, with the script as an argument. It also forwards arguments.
|
||||
# ------------
|
||||
# `sbang` is a very simple posix shell script. It looks at the first two
|
||||
# lines of a script argument and runs the last line starting with `#!`,
|
||||
# with the script as an argument. It also forwards arguments.
|
||||
#
|
||||
|
||||
# We disable two shellcheck errors below:
|
||||
# SC2124: when saving arguments, we intentionally assign as an array
|
||||
# SC2086: when splitting $shebang_line and exec args, we want to expand args
|
||||
|
||||
# Generic error handling
|
||||
die() {
|
||||
echo "$@" 1>&2;
|
||||
exit 1
|
||||
}
|
||||
|
||||
# set SBANG_DEBUG to make the script print what would normally be executed.
|
||||
exec="exec"
|
||||
if [ -n "${SBANG_DEBUG}" ]; then
|
||||
exec="echo "
|
||||
fi
|
||||
|
||||
# First argument is the script we want to actually run.
|
||||
script="$1"
|
||||
|
||||
# ensure that the script actually exists
|
||||
if [ -z "$script" ]; then
|
||||
die "error: sbang requires exactly one argument"
|
||||
elif [ ! -f "$script" ]; then
|
||||
die "$script: no such file or directory"
|
||||
fi
|
||||
|
||||
# Search the first two lines of script for interpreters.
|
||||
lines=0
|
||||
while read line && ((lines < 2)) ; do
|
||||
if [[ "$line" = '#!'* ]]; then
|
||||
interpreter="${line#\#!}"
|
||||
elif [[ "$line" = '//!'*node* ]]; then
|
||||
interpreter="${line#//!}"
|
||||
elif [[ "$line" = '--!'*lua* ]]; then
|
||||
interpreter="${line#--!}"
|
||||
elif [[ "$line" = '<?php #!'*php* ]]; then
|
||||
interpreter="${line#<?php\ \#!}"
|
||||
interpreter="${interpreter%\ ?>}"
|
||||
while read -r line && [ $lines -ne 2 ]; do
|
||||
if [ "${line#\#!}" != "$line" ]; then
|
||||
shebang_line="${line#\#!}"
|
||||
elif [ "${line#//!}" != "$line" ]; then # // comments
|
||||
shebang_line="${line#//!}"
|
||||
elif [ "${line#--!}" != "$line" ]; then # -- lua comments
|
||||
shebang_line="${line#--!}"
|
||||
elif [ "${line#<?php\ }" != "$line" ]; then # php comments
|
||||
shebang_line="${line#<?php\ \#!}"
|
||||
shebang_line="${shebang_line%\ ?>}"
|
||||
fi
|
||||
lines=$((lines+1))
|
||||
done < "$script"
|
||||
# this is ineeded for scripts with sbang parameter
|
||||
# like ones in intltool
|
||||
# #!/<spack-long-path>/perl -w
|
||||
# this is the interpreter line with all the parameters as a vector
|
||||
interpreter_v=(${interpreter})
|
||||
# this is the single interpreter path
|
||||
interpreter_f="${interpreter_v[0]}"
|
||||
|
||||
# Invoke any interpreter found, or raise an error if none was found.
|
||||
if [[ -n "$interpreter_f" ]]; then
|
||||
if [[ "${interpreter_f##*/}" = "perl"* ]]; then
|
||||
exec $interpreter -x "$@"
|
||||
else
|
||||
exec $interpreter "$@"
|
||||
fi
|
||||
else
|
||||
echo "error: sbang found no interpreter in $script"
|
||||
exit 1
|
||||
# shellcheck disable=SC2124
|
||||
# this saves arguments for later and intentionally assigns as an array
|
||||
args="$@"
|
||||
|
||||
# handle scripts with sbang parameters, e.g.:
|
||||
#
|
||||
# #!/<spack-long-path>/perl -w
|
||||
#
|
||||
# put the shebang line with all the parameters in the $@ array and get
|
||||
# the first element.
|
||||
# shellcheck disable=SC2086
|
||||
set $shebang_line
|
||||
set -- "$@"
|
||||
interpreter="$1"
|
||||
arg1="$2"
|
||||
|
||||
# error if we did not find any interpreter
|
||||
if [ -z "$interpreter" ]; then
|
||||
die "error: sbang found no interpreter in $script"
|
||||
fi
|
||||
|
||||
# Determine if the interpreter is a particular program, accounting for the
|
||||
# '#!/usr/bin/env PROGRAM' convention. So:
|
||||
#
|
||||
# interpreter_is perl
|
||||
#
|
||||
# will be true for '#!/usr/bin/perl' and '#!/usr/bin/env perl'
|
||||
interpreter_is() {
|
||||
if [ "${interpreter##*/}" = "$1" ]; then
|
||||
return 0
|
||||
elif [ "$interpreter" = "/usr/bin/env" ] && [ "$arg1" = "$1" ]; then
|
||||
return 0
|
||||
else
|
||||
return 1
|
||||
fi
|
||||
}
|
||||
|
||||
if interpreter_is "sbang"; then
|
||||
die "error: refusing to re-execute sbang to avoid infinite loop."
|
||||
fi
|
||||
|
||||
# Finally invoke the real shebang line
|
||||
# ruby and perl need -x to ignore the first line of input (the sbang line)
|
||||
#
|
||||
if interpreter_is perl || interpreter_is ruby; then
|
||||
# shellcheck disable=SC2086
|
||||
$exec $shebang_line -x "$args"
|
||||
else
|
||||
# shellcheck disable=SC2086
|
||||
$exec $shebang_line "$args"
|
||||
fi
|
||||
|
||||
Reference in New Issue
Block a user