I wish to have long and short forms of command line options invoked using my shell script.
I know that getopts can be used, but like in Perl, I have not been able to do the same with shell.
Any ideas on how this can be done, so that I can use options like:
./shell.sh --copyfile abc.pl /tmp/
./shell.sh -c abc.pl /tmp/
In the above, both the commands mean the same thing to my shell, but using getopts, I have not been able to implement these?
There are three implementations that may be considered:
Bash builtin getopts. This does not support long option names with the double-dash prefix. It only supports single-character options.
BSD UNIX implementation of standalone getopt command (which is what MacOS uses). This does not support long options either.
GNU implementation of standalone getopt. GNU getopt(3) (used by the command-line getopt(1) on Linux) supports parsing long options.
Some other answers show a solution for using the bash builtin getopts to mimic long options. That solution actually makes a short option whose character is "-". So you get "--" as the flag. Then anything following that becomes OPTARG, and you test the OPTARG with a nested case.
This is clever, but it comes with caveats:
getopts can't enforce the opt spec. It can't return errors if the user supplies an invalid option. You have to do your own error-checking as you parse OPTARG.So while it is possible to write more code to work around the lack of support for long options, this is a lot more work and partially defeats the purpose of using a getopt parser to simplify your code.
The built-in getopts command is still, AFAIK, limited to single-character options only.
There is (or used to be) an external program getopt that would reorganize a set of options such that it was easier to parse. You could adapt that design to handle long options too. Example usage:
aflag=no
bflag=no
flist=""
set -- $(getopt abf: "$@")
while [ $# -gt 0 ]
do
case "$1" in
(-a) aflag=yes;;
(-b) bflag=yes;;
(-f) flist="$flist $2"; shift;;
(--) shift; break;;
(-*) echo "$0: error - unrecognized option $1" 1>&2; exit 1;;
(*) break;;
esac
shift
done
# Process remaining non-option arguments
...
You could use a similar scheme with a getoptlong command.
Note that the fundamental weakness with the external getopt program is the difficulty of handling arguments with spaces in them, and in preserving those spaces accurately. This is why the built-in getopts is superior, albeit limited by the fact it only handles single-letter options.
Take a look at shFlags which is a portable shell library (meaning: sh, bash, dash, ksh, zsh on Linux, Solaris, etc.).
It makes adding new flags as simple as adding one line to your script, and it provides an auto generated usage function.
Here is a simple Hello, world! using shFlag:
#!/bin/sh
# source shflags from current directory
. ./shflags
# define a 'name' command-line string flag
DEFINE_string 'name' 'world' 'name to say hello to' 'n'
# parse the command-line
FLAGS "$@" || exit 1
eval set -- "${FLAGS_ARGV}"
# say hello
echo "Hello, ${FLAGS_name}!"
For OSes that have the enhanced getopt that supports long options (e.g. Linux), you can do:
$ ./hello_world.sh --name Kate
Hello, Kate!
For the rest, you must use the short option:
$ ./hello_world.sh -n Kate
Hello, Kate!
Adding a new flag is as simple as adding a new DEFINE_ call.
In case you don't want the getopt dependency, you can do this:
while test $# -gt 0
do
case $1 in
# Normal option processing
-h | --help)
# usage and help
;;
-v | --version)
# version info
;;
# ...
# Special cases
--)
break
;;
--*)
# error unknown (long) option $1
;;
-?)
# error unknown (short) option $1
;;
# FUN STUFF HERE:
# Split apart combined short options
-*)
split=$1
shift
set -- $(echo "$split" | cut -c 2- | sed 's/./-& /g') "$@"
continue
;;
# Done with options
*)
break
;;
esac
# for testing purposes:
echo "$1"
shift
done
Of course, then you can't use long style options with one dash. And if you want to add shortened versions (e.g. --verbos instead of --verbose), then you need to add those manually.
But if you are looking to get getopts functionality along with long options, this is a simple way to do it.
I also put this snippet in a gist.
The built-in getopts can't do this. There is an external getopt(1) program that can do this, but you only get it on Linux from the util-linux package. It comes with an example script getopt-parse.bash.
There is also a getopts_long written as a shell function.
In ksh93, getopts does support long names...
while getopts "f(file):s(server):" flag
do
echo "$flag" $OPTIND $OPTARG
done
Or so the tutorials I have found have said. Try it and see.
The accepted answer does a very nice job of pointing out all the shortcomings of bash built-in getopts. The answer ends with:
So while it is possible to write more code to work around the lack of support for long options, this is a lot more work and partially defeats the purpose of using a getopt parser to simplify your code.
And even though I agree in principle with that statement, I feel that the number of times we all implemented this feature in various scripts justifies putting a bit of effort into creating a "standardised", well tested solution.
As such, I've "upgraded" bash built in getopts by implementing getopts_long in pure bash, with no external dependencies. The usage of the function is 100% compatible with the built-in getopts.
By including getopts_long (which is hosted on GitHub) in a script, the answer to the original question can be implemented as simply as:
source "${PATH_TO}/getopts_long.bash"
while getopts_long ':c: copyfile:' OPTKEY; do
case ${OPTKEY} in
'c'|'copyfile')
echo 'file supplied -- ${OPTARG}'
;;
'?')
echo "INVALID OPTION -- ${OPTARG}" >&2
exit 1
;;
':')
echo "MISSING ARGUMENT for option -- ${OPTARG}" >&2
exit 1
;;
*)
echo "Misconfigured OPTSPEC or uncaught option -- ${OPTKEY}" >&2
exit 1
;;
esac
done
shift $(( OPTIND - 1 ))
[[ "${1}" == "--" ]] && shift
I only write shell scripts now and then and fall out of practice, so any feedback is appreciated.
Using the strategy proposed by @Arvid Requate, we noticed some user errors. A user who forgets to include a value will accidentally have the next option's name treated as a value:
./getopts_test.sh --loglevel= --toc=TRUE
will cause the value of "loglevel" to be seen as "--toc=TRUE". This can be avoided.
I adapted some ideas about checking user error for CLI from http://mwiki.wooledge.org/BashFAQ/035 discussion of manual parsing. I inserted error checking into handling both "-" and "--" arguments.
Then I started fiddling around with the syntax, so any errors in here are strictly my fault, not the original authors.
My approach helps users who prefer to enter long with or without the equal sign. That is, it should have same response to "--loglevel 9" as "--loglevel=9". In the --/space method, it is not possible to know for sure if the user forgets an argument, so some guessing is needed.
In case you are starting out on this, there is an interesting difference between "--opt=value" and "--opt value" formats. With the equal sign, the command line argument is seen as "opt=value" and the work to handle that is string parsing, to separate at the "=". In contrast, with "--opt value", the name of the argument is "opt" and we have the challenge of getting the next value supplied in the command line. That's where @Arvid Requate used ${!OPTIND}, the indirect reference. I still don't understand that, well, at all, and comments in BashFAQ seem to warn against that style (http://mywiki.wooledge.org/BashFAQ/006). BTW, I don't think previous poster's comments about importance of OPTIND=$(( $OPTIND + 1 )) are correct. I mean to say, I see no harm from omitting it.
In newest version of this script, flag -v means VERBOSE printout.
Save it in a file called "cli-5.sh", make executable, and any of these will work, or fail in the desired way
./cli-5.sh -v --loglevel=44 --toc TRUE
./cli-5.sh -v --loglevel=44 --toc=TRUE
./cli-5.sh --loglevel 7
./cli-5.sh --loglevel=8
./cli-5.sh -l9
./cli-5.sh --toc FALSE --loglevel=77
./cli-5.sh --toc=FALSE --loglevel=77
./cli-5.sh -l99 -t yyy
./cli-5.sh -l 99 -t yyy
Here is example output of the error-checking on user intpu
$ ./cli-5.sh --toc --loglevel=77
ERROR: toc value must not have dash at beginning
$ ./cli-5.sh --toc= --loglevel=77
ERROR: value for toc undefined
You should consider turning on -v, because it prints out internals of OPTIND and OPTARG
#/usr/bin/env bash
## Paul Johnson
## 20171016
##
## Combines ideas from
## https://stackoverflow.com/questions/402377/using-getopts-in-bash-shell-script-to-get-long-and-short-command-line-options
## by @Arvid Requate, and http://mwiki.wooledge.org/BashFAQ/035
# What I don't understand yet:
# In @Arvid REquate's answer, we have
# val="${!OPTIND}"; OPTIND=$(( $OPTIND + 1 ))
# this works, but I don't understand it!
die() {
printf '%s\n' "$1" >&2
exit 1
}
printparse(){
if [ ${VERBOSE} -gt 0 ]; then
printf 'Parse: %s%s%s\n' "$1" "$2" "$3" >&2;
fi
}
showme(){
if [ ${VERBOSE} -gt 0 ]; then
printf 'VERBOSE: %s\n' "$1" >&2;
fi
}
VERBOSE=0
loglevel=0
toc="TRUE"
optspec=":vhl:t:-:"
while getopts "$optspec" OPTCHAR; do
showme "OPTARG: ${OPTARG[*]}"
showme "OPTIND: ${OPTIND[*]}"
case "${OPTCHAR}" in
-)
case "${OPTARG}" in
loglevel) #argument has no equal sign
opt=${OPTARG}
val="${!OPTIND}"
## check value. If negative, assume user forgot value
showme "OPTIND is {$OPTIND} {!OPTIND} has value \"${!OPTIND}\""
if [[ "$val" == -* ]]; then
die "ERROR: $opt value must not have dash at beginning"
fi
## OPTIND=$(( $OPTIND + 1 )) # CAUTION! no effect?
printparse "--${OPTARG}" " " "${val}"
loglevel="${val}"
shift
;;
loglevel=*) #argument has equal sign
opt=${OPTARG%=*}
val=${OPTARG#*=}
if [ "${OPTARG#*=}" ]; then
printparse "--${opt}" "=" "${val}"
loglevel="${val}"
## shift CAUTION don't shift this, fails othewise
else
die "ERROR: $opt value must be supplied"
fi
;;
toc) #argument has no equal sign
opt=${OPTARG}
val="${!OPTIND}"
## check value. If negative, assume user forgot value
showme "OPTIND is {$OPTIND} {!OPTIND} has value \"${!OPTIND}\""
if [[ "$val" == -* ]]; then
die "ERROR: $opt value must not have dash at beginning"
fi
## OPTIND=$(( $OPTIND + 1 )) #??
printparse "--${opt}" " " "${val}"
toc="${val}"
shift
;;
toc=*) #argument has equal sign
opt=${OPTARG%=*}
val=${OPTARG#*=}
if [ "${OPTARG#*=}" ]; then
toc=${val}
printparse "--$opt" " -> " "$toc"
##shift ## NO! dont shift this
else
die "ERROR: value for $opt undefined"
fi
;;
help)
echo "usage: $0 [-v] [--loglevel[=]<value>] [--toc[=]<TRUE,FALSE>]" >&2
exit 2
;;
*)
if [ "$OPTERR" = 1 ] && [ "${optspec:0:1}" != ":" ]; then
echo "Unknown option --${OPTARG}" >&2
fi
;;
esac;;
h|-\?|--help)
## must rewrite this for all of the arguments
echo "usage: $0 [-v] [--loglevel[=]<value>] [--toc[=]<TRUE,FALSE>]" >&2
exit 2
;;
l)
loglevel=${OPTARG}
printparse "-l" " " "${loglevel}"
;;
t)
toc=${OPTARG}
;;
v)
VERBOSE=1
;;
*)
if [ "$OPTERR" != 1 ] || [ "${optspec:0:1}" = ":" ]; then
echo "Non-option argument: '-${OPTARG}'" >&2
fi
;;
esac
done
echo "
After Parsing values
"
echo "loglevel $loglevel"
echo "toc $toc"
if simply this is how you want to call the script
myscript.sh --input1 "ABC" --input2 "PQR" --input2 "XYZ"
then you can follow this simplest way to achieve it with the help of getopt and --longoptions
try this , hope this is useful
# Read command line options
ARGUMENT_LIST=(
"input1"
"input2"
"input3"
)
# read arguments
opts=$(getopt \
--longoptions "$(printf "%s:," "${ARGUMENT_LIST[@]}")" \
--name "$(basename "$0")" \
--options "" \
-- "$@"
)
echo $opts
eval set --$opts
while true; do
case "$1" in
--input1)
shift
empId=$1
;;
--input2)
shift
fromDate=$1
;;
--input3)
shift
toDate=$1
;;
--)
shift
break
;;
esac
shift
done
A simple DIY to get only long named args:
Use:
$ ./test-args.sh --a1 a1 --a2 "a 2" --a3 --a4= --a5=a5 --a6="a 6"
a1 = "a1"
a2 = "a 2"
a3 = "TRUE"
a4 = ""
a5 = "a5"
a6 = "a 6"
a7 = ""
Script:
#!/bin/bash
function main() {
ARGS=`getArgs "$@"`
a1=`echo "$ARGS" | getNamedArg a1`
a2=`echo "$ARGS" | getNamedArg a2`
a3=`echo "$ARGS" | getNamedArg a3`
a4=`echo "$ARGS" | getNamedArg a4`
a5=`echo "$ARGS" | getNamedArg a5`
a6=`echo "$ARGS" | getNamedArg a6`
a7=`echo "$ARGS" | getNamedArg a7`
echo "a1 = \"$a1\""
echo "a2 = \"$a2\""
echo "a3 = \"$a3\""
echo "a4 = \"$a4\""
echo "a5 = \"$a5\""
echo "a6 = \"$a6\""
echo "a7 = \"$a7\""
exit 0
}
function getArgs() {
for arg in "$@"; do
echo "$arg"
done
}
function getNamedArg() {
ARG_NAME=$1
sed --regexp-extended --quiet --expression="
s/^--$ARG_NAME=(.*)\$/\1/p # Get arguments in format '--arg=value': [s]ubstitute '--arg=value' by 'value', and [p]rint
/^--$ARG_NAME\$/ { # Get arguments in format '--arg value' ou '--arg'
n # - [n]ext, because in this format, if value exists, it will be the next argument
/^--/! p # - If next doesn't starts with '--', it is the value of the actual argument
/^--/ { # - If next do starts with '--', it is the next argument and the actual argument is a boolean one
# Then just repla[c]ed by TRUE
c TRUE
}
}
"
}
main "$@"