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Enable long, GNU style options RE: issue-1 #3

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merged 2 commits into from
Feb 16, 2016
Merged

Enable long, GNU style options RE: issue-1 #3

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bfb8d40
Enable long, GNU style options
zbeekman Feb 16, 2016
9d2bcdb
Update expected test output
zbeekman Feb 16, 2016
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96 changes: 64 additions & 32 deletions main.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -24,16 +24,27 @@
### Configuration
#####################################################################

# Exit on error. Append ||true if you expect an error.
# `set` is safer than relying on a shebang like `#!/bin/bash -e` because that is neutralized
# when someone runs your script as `bash yourscript.sh`
set -o errexit
set -o nounset

# Bash will remember & return the highest exitcode in a chain of pipes.
# This way you can catch the error in case mysqldump fails in `mysqldump |gzip`
set -o pipefail

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More robust error checking from the beginning

# Environment variables and their defaults
LOG_LEVEL="${LOG_LEVEL:-6}" # 7 = debug -> 0 = emergency

# Commandline options. This defines the usage page, and is used to parse cli
# opts & defaults from. The parsing is unforgiving so be precise in your syntax
read -r -d '' usage <<-'EOF'
-f [arg] Filename to process. Required.
-t [arg] Location of tempfile. Default="/tmp/bar"
-d Enables debug mode
-h This page
read -r -d '' usage <<-'EOF' || true # exits non-zero when EOF encountered
-f --file [arg] Filename to process. Required.
-t --temp [arg] Location of tempfile. Default="/tmp/bar"
-v Enable verbose mode, print script as it is executed
-d --debug Enables debug mode
-h --help This page
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The second field is examined for leading -- if found, that is determined to be a long version of the option. N.B. All long options must have corresponding short options, but not vice-versa. This could be changed without too much work, but for now, this is more consistent with the existing code and intentions, IMO.

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A very acceptable compromise imo too

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👍

EOF

# Set magic variables for current file and its directory.
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I had to delete the whitespace at EOL error... because OCD

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Yes of course : ) I think I have turned it off in my editor for markdown trailing space preservation. I should really make a case-by-case exception going forward 😄

Expand All @@ -56,7 +67,7 @@ function _fmt () {
fi

local color_reset="\x1b[0m"
if [[ "${TERM}" != "xterm"* ]] || [ -t 1 ]; then
if [[ "${TERM:-}" != "xterm"* ]] || [ -t 1 ]; then
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Allow some variables to be unset, without causing errors, mostly those provided by the system and built-ins that should be set in most reasonable environments, but if not, they won't cause problems.

# Don't use colors on pipes or non-recognized terminals
color=""; color_reset=""
fi
Expand Down Expand Up @@ -91,14 +102,26 @@ trap cleanup_before_exit EXIT

# Translate usage string -> getopts arguments, and set $arg_<flag> defaults
while read line; do
opt="$(echo "${line}" |awk '{print $1}' |sed -e 's#^-##')"
# fetch single character version of option sting
opt="$(echo "${line}" |awk 'match($1,"^-.",a){print substr(a[0],2,1)}')"

# fetch long version if present
long_opt="$(echo "${line}" |awk 'match($2,"^--.*",a){print substr(a[0],3)}')"
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Get the long option name from the second field, if it exists

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I think it would be cool to use one method for long/short opt parsing. E.g. go awk only for both?

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Sure I can do that

# map long name back to short name
varname="short_opt_${long_opt}"
eval "${varname}=\"${opt}\""
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We'll use this later to make long options get processed as if the short option was used


# check if option takes an argument
varname="has_arg_${opt}"
if ! echo "${line}" |egrep '\[.*\]' >/dev/null 2>&1; then
init="0" # it's a flag. init with 0
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This line was unused, dead code so I removed it.

eval "${varname}=0"
else
opt="${opt}:" # add : if opt has arg
init="" # it has an arg. init with ""
eval "${varname}=1"
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We need some additional means of determining whether the long options have required arguments or not; the : doesn't apply in the normal sense to them

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It seems that even before these changes, if a required option argument was missing, subsequent options/text would get parsed as the required argument. It might be sensible to check that required arguments aren't just being populated with additional options/arguments. See also #5

fi
opts="${opts}${opt}"
opts="${opts:-}${opt}"

varname="arg_${opt:0:1}"
if ! echo "${line}" |egrep '\. Default=' >/dev/null 2>&1; then
Expand All @@ -109,30 +132,44 @@ while read line; do
fi
done <<< "${usage}"

# Allow long options like --this
opts="${opts}-:"

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This is the trick. I saw it here: http://mywiki.wooledge.org/ComplexOptionParsing (second code block)

# Reset in case getopts has been used previously in the shell.
OPTIND=1

# Overwrite $arg_<flag> defaults with the actual CLI options
while getopts "${opts}" opt; do
line="$(echo "${usage}" |grep "\-${opt}")"
[ "${opt}" = "?" ] && help "Invalid use of script: ${@} "

if [ "${opt}" = "-" ]; then #OPTARG is long-option-name or long-option=value
if [[ "${OPTARG}" =~ .*=.* ]]; then # --key=value format
long=${OPTARG/=*/}
eval "opt=\"\${short_opt_${long}}\"" # Set opt to the short option corresponding to the long option
OPTARG=${OPTARG#*=}
else # --key value format
eval "opt=\"\${short_opt_${OPTARG}}\"" # Map long name to short version of option
eval "OPTARG=\"\${@:OPTIND:\${has_arg_${opt}}}\"" # Only assign OPTARG if option takes an argument
((OPTIND+=has_arg_${opt})) # shift over the argument if argument is expected
fi
# we have set opt/OPTARG to the short value and the argument as OPTARG if it exists
else
varname="arg_${opt:0:1}"
default="${!varname}"

[ "${opt}" = "?" ] && help "Invalid use of script: ${@} "
varname="arg_${opt:0:1}"
default="${!varname}"
value="${OPTARG:-}"
if [ -z "${OPTARG:-}" ] && [ "${default}" = "0" ]; then
value="1"
fi

value="${OPTARG}"
if [ -z "${OPTARG}" ] && [ "${default}" = "0" ]; then
value="1"
eval "${varname}=\"${value}\""
debug "cli arg ${varname} = ($default) -> ${!varname}"
fi

eval "${varname}=\"${value}\""
debug "cli arg ${varname} = ($default) -> ${!varname}"
done

shift $((OPTIND-1))

[ "$1" = "--" ] && shift
[ "${1:-}" = "--" ] && shift


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Move to beginning for better error handling

### Switches (like -d for debugmode, -h for showing helppage)
Expand All @@ -144,6 +181,11 @@ if [ "${arg_d}" = "1" ]; then
LOG_LEVEL="7"
fi

# verbose mode
if [ "${arg_v}" = "1" ]; then
set -o verbose
fi

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This hunk is just related to the additional -v flag.... could easily remove this and the extra definition in the usage string

# help mode
if [ "${arg_h}" = "1" ]; then
# Help exists with code 1
Expand All @@ -154,24 +196,14 @@ fi
### Validation (decide what's required for running your script and error out)
#####################################################################

[ -z "${arg_f}" ] && help "Setting a filename with -f is required"
[ -z "${LOG_LEVEL}" ] && emergency "Cannot continue without LOG_LEVEL. "
[ -z "${arg_f:-}" ] && help "Setting a filename with -f or --file is required"
[ -z "${LOG_LEVEL:-}" ] && emergency "Cannot continue without LOG_LEVEL. "


### Runtime
#####################################################################

# Exit on error. Append ||true if you expect an error.
# `set` is safer than relying on a shebang like `#!/bin/bash -e` because that is neutralized
# when someone runs your script as `bash yourscript.sh`
set -o errexit
set -o nounset

# Bash will remember & return the highest exitcode in a chain of pipes.
# This way you can catch the error in case mysqldump fails in `mysqldump |gzip`
set -o pipefail

if [[ "${OSTYPE}" == "darwin"* ]]; then
if [[ "${OSTYPE:-}" == "darwin"* ]]; then
info "You are on OSX"
else
info "You are on Linux"
Expand Down
9 changes: 5 additions & 4 deletions test/fixture/help.stdio
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Expand Up @@ -2,9 +2,10 @@ B3BP:STDIO_REPLACE_DATETIMES

Help using {root}/main.sh

-f [arg] Filename to process. Required.
-t [arg] Location of tempfile. Default="{tmpdir}/bar"
-d Enables debug mode
-h This page
-f --file [arg] Filename to process. Required.
-t --temp [arg] Location of tempfile. Default="{tmpdir}/bar"
-v Enable verbose mode, print script as it is executed
-d --debug Enables debug mode
-h --help This page

{datetime} UTC [ info] Cleaning up. Done