I need help with my getopts, i want to be able to run this command ( mount command) only if i pass a flag ( -d in this case).
below output is what i have on my script but it doesn't seem to work.
CHECKMOUNT=" "
while getopts ":d" opt
do
case "$opt" in
d) CHECKMOUNT="true" ;;
usage >&2
exit 1;;
esac
done
shift `expr $OPTIND-1`
FS_TO_CHECK="/dev"
if [ "$CHECKMOUNT" = "true" ]
then
if cat /proc/mounts | grep $FS_TO_CHECK > /dev/null; then
# Filesystem is mounted
else
# Filesystem is not mounted
fi
fi
Your script has a number of problems.
Here is the minimal list of fixes to get it working:
While is not a bash control statement, it's while. Case is important.
Whitespace is important: if ["$CHECKMOUNT"= "true"] doesn't work and should cause error messages. You need spaces around the brackets and around the =, like so: if [ "$CHECKMOUNT" = "true" ].
Your usage of getopts is incorrect, I'm guessing that you mistyped this copying an example: While getopts :d: opt should be: while getopts ":d" opt.
Your usage of shift is incorrect. This should cause error messages. Change this to: shift $((OPTIND-1)) if you need to shift OPTIND.
The bare text unknocn flag seems like a comment, precede it with #, otherwise you'll get an error when using an unknown option.
There is no usage function. Define one, or change usage in your \?) case to an echo with usage instructions.
Finally, if your script only requires a single optional argument, you might also simply process it yourself instead of using getopt - the first argument to your script is stored in the special variable $1:
if [ "$1" = "-d" ]; then
CHECKMOUNT="true"
elif [ "$1" != "" ]; then
usage >&2
exit 1
fi
Related
I'm a Bash newbie, and I'm puzzling through a Bash script where I see this:
while [ $# -ge 2 ]
if [ "x$1" = "x-a" ]; then
echo "STR_A = $2" >>tmpFile.txt
...do more stuff...
elif [ "x$1" = "x-b" ]; then
echo "STR_B = $2" >>tmpFile.txt
...do more stuff...
else
usage
done
The script takes in four (or five?) command line arguments, and that usage function is:
usage() {
echo "usage: myscript -a STR_A | -b STR_B" 1>&2
exit 1
}
So suppose I ran the script like this:
me#ubuntu1:~$./myscript -A apple -B banana
I'm guessing that this code processes the script's command line arguments. I think that the outer while() loop steps through the command line arguments after argument 1, which would be myscript. The inner if() statements check to see an -a or -b flag is used to supply arguments, and then records the text string that follows in tmpFile.txt. Anything outside of those parameters is rejected and the script exits.
A lot of these assumptions rest on the bet that the outer while() loop...
while [ $# -ge 2 ]
...means "parse the BASH argv[] after the first argument", (to put this in C terms.) If that's not a correct assumption, then I have no idea what's going on here. Any feedback is appreciated, thank you!
Some code explanation.
while [ $# -ge 2 ]
There is a missing do for the loop.
This should loop forever if there are two or more arguments, unless shift is used. If there are less than two arguments, the loop does not even start.
if [ "x$1" = "x-a" ]; then
In distant past, it was common to prevent empty strings by adding an extra letter. Nowadays you would if [ "$1" = "-a" ]; then.
else
usage
Note that the usage is called from within the loop. So, if I would call the script as myscript -a, I would not get a usage message. On the other hand, if I would myscript bla bla, I would get an endless stream of error messages, which is probably not what you want.
I would seriously edit the script; determine whether the while is indeed a loop-forever or whether it is used instead of an if, and try the getops for argument parsing.
This doesn't help understand the code you're reading, but I do option parsing like this:
# inititialize vars, not strictly required in this case
a=''
b=''
# process options
while getopts "ha:b:" opt; do
case $opt in
a) a=$OPTARG ;;
b) b=$OPTARG ;;
*) usage ;;
esac
done
# shift after the processing
shift $((OPTIND - 1))
# look for error conditions
if [[ -n $a && -n $b ]]; then
echo "only one of -a or -b should be given" >&2
exit 1
fi
getopts is a bash builtin
So I have a couple of getopts in my bash script. Here's an example of a working one.
FOUND=
SEARCH=
COUNT=0
while getopts "ips:flenkc" OPTION
do
case $OPTION in
i)
FOUND=1
let "COUNT++"
;;
p)
FOUND=2
let "COUNT++"
;;
s)
FOUND=3
SEARCH=$OPTARG
let "COUNT++"
;;
esac
done
Later on a case statement that checks to see if count=1 (meaning, only one of the following, i, p, and s, are used in the call) Not important except that it determines the main action being done.
Now the getopts thing in question. This was working before, and now it's not. The goal is to make it so that if someone wants to input data, they can do so with the following bash command.
./programname -i -f Mary -l Sue -e smary#email.com -n 555-555-5555
Where, when -i is used, we must have -f, -l, -e, and -n (for first name, last name, e-mail, and number).
The code I was using: Warning, code is full of syntax errors. If you're learning bash, I highly recommend you do not use anything you see here in my post.
if [ $FOUND == "1" ]
then
echo "You have chosen to insert things."
FIRST=
LAST=
EMAIL=
NUMBER=
while getopts "if:l:e:n:" OPTION
do
case $OPTION in
f)
FIRST=$OPTARG
;;
l)
LAST=$OPTARG
;;
e)
EMAIL=$OPTARG
;;
n)
NUMBER=$OPTARG
;;
esac
done
if [[ -z $FIRST ]] || [[ -z $LAST ]] || [[ -z $EMAIL ]] || [[ -z $NUMBER ]]
echo "Error!!! Some input is missing!!!"
usage // display usage
exit 1
fi
echo -e $FIRST"\t"$LAST"\t"$EMAIL"\t"$NUMBER >> contacts
fi
Before this program would work, but now, not even a single thing is making it to input for FIRST, LAST, EMAIL, and NUMBER (in my attempts to change the code to see if it was making it to certain steps).
What am I doing wrong with the getopts? It was working fine before, but now.... it's not working at all!
One thing worth noting up front: if your script has already called getopts once, another getopts call will start AFTER all options and therefore effectively do nothing; reset OPTIND to 1 before each subsequent getopts calls to have them reprocess all options.
Your code has both syntax errors and is worth cleaning up in general:
The if [[ -z ... statement was missing a then.
The // after usage would have caused a syntax error - POSIX-like shells use # as the comment char.
Since this is bash script, stick with using [[ ... ]] consistently (no need for [ ... ]) and/or use (( ... )) for arithmetic operations.
Specifically, avoid [ ... == ... ], because it mixes POSIX syntax - [ ... ] - with Bash-specific syntax - == ( POSIX only supports =).
If you do use [ ... ], be sure to double-quote variable references, to be safe.
No need for multiple [[ ... ]] expressions to OR them together - do it in a single [[ ... || ... || ... ]].
It's best to avoid all-uppercase shell-variable names so as to avoid conflicts with environment variables and special shell variables.
Output error messages to stderr, using >&2.
Enclose the entire argument to echo -e in double-quotes to protect variable values from possibly unwanted expansions.
Mere syntax errors can usually be caught using shellcheck.net.
Putting it all together, we get:
#!/usr/bin/env bash
# ... code that sets $found
# If you've already processed args. with getopts above,
# you must reset OPTIND to process them again.
OPTIND=1
if (( found == 1 )) # found is numeric, use arithmetic expression to compare
then
echo "You have chosen to insert things."
first= last= email= number= # don't use all-uppercase var. names
while getopts "if:l:e:n:" option
do
case $option in
f)
first=$OPTARG
;;
l)
last=$OPTARG
;;
e)
email=$OPTARG
;;
n)
number=$OPTARG
;;
esac
done
if [[ -z $first || -z $last || -z $email || -z $number ]]; then
echo "Error!!! Some input is missing!!!" >&2
usage # display usage
exit 1
fi
echo -e "$first\t$last\t$email\t$number" >> contacts
fi
So I've been reading around about getopts, getopt, etc. but I haven't found an exact solution to my problem.
The basic idea of the usage of my script is:
./program [-u] [-s] [-d] <TEXT>
Except TEXT is not required if -d is passed. Note that TEXT is usually a paragraph of text.
My main problem is that once getopts finishing parsing the flags, I have no way of knowing the position of the TEXT parameter. I could just assume that TEXT is the last argument, however, if a user messes up and does something like:
./program -u "sentence 1" "sentence 2"
then the program will not realize that the usage is incorrect.
The closest I've come is using getopt and IFS by doing
ARGS=$(getopt usd: $*)
IFS=' ' read -a array <<< "$ARGS"
The only problem is that TEXT might be a long paragraph of text and this method splits every word of text because of the spaces.
I'm thinking my best bet is to use a regular expression to ensure the usage is correctly formed and then extract the arguments with getopts, but it would be nice if there was a simpler solution
It's quite simple with getopts:
#!/bin/bash
u_set=0
s_set=0
d_set=0
while getopts usd OPT; do
case "$OPT" in
u) u_set=1;;
s) s_set=1;;
d) d_set=1;;
*) # getopts produces error
exit 1;;
esac
done
if ((!d_set && OPTIND>$#)); then
echo You must provide text or use -d >>/dev/stderr
exit 1
fi
# The easiest way to get rid of the processed options:
shift $((OPTIND-1))
# This will run all of the remaining arguments together with spaces between them:
TEXT="$*"
This is what I typically do:
local badflag=""
local aflag=""
local bflag=""
local cflag=""
local dflag=""
while [[ "$1" == -* ]]; do
case $1 in
-a)
aflag="-a"
;;
-b)
bflag="-b"
;;
-c)
cflag="-c"
;;
-d)
dflag="-d"
;;
*)
badflag=$1
;;
esac
shift
done
if [ "$badflag" != "" ]; do
echo "ERROR CONDITION"
fi
if [ "$1" == "" ] && [ "$dflag" == "" ]; do
echo "ERROR CONDITION"
fi
local remaining_text=$#
I'd like to be able to accept both mandatory and optional flags in my script. Here's what I have so far.
#!bin/bash
while getopts ":a:b:cdef" opt; do
case $opt in
a ) APPLE="$OPTARG";;
b ) BANANA="$OPTARG";;
c ) CHERRY="$OPTARG";;
d ) DFRUIT="$OPTARG";;
e ) EGGPLANT="$OPTARG";;
f ) FIG="$OPTARG";;
\?) echo "Invalid option: -"$OPTARG"" >&2
exit 1;;
: ) echo "Option -"$OPTARG" requires an argument." >&2
exit 1;;
esac
done
echo "Apple is "$APPLE""
echo "Banana is "$BANANA""
echo "Cherry is "$CHERRY""
echo "Dfruit is "$DFRUIT""
echo "Eggplant is "$EGGPLANT""
echo "Fig is "$FIG""
However, the output for the following:
bash script.sh -a apple -b banana -c cherry -d dfruit -e eggplant -f fig
...outputs this:
Apple is apple
Banana is banana
Cherry is
Dfruit is
Eggplant is
Fig is
As you can see, the optional flags are not pulling the arguments with $OPTARG as it does with the required flags. Is there a way to read $OPTARG on optional flags without getting rid of the neat ":)" error handling?
=======================================
EDIT: I wound up following the advice of Gilbert below. Here's what I did:
#!/bin/bash
if [[ "$1" =~ ^((-{1,2})([Hh]$|[Hh][Ee][Ll][Pp])|)$ ]]; then
print_usage; exit 1
else
while [[ $# -gt 0 ]]; do
opt="$1"
shift;
current_arg="$1"
if [[ "$current_arg" =~ ^-{1,2}.* ]]; then
echo "WARNING: You may have left an argument blank. Double check your command."
fi
case "$opt" in
"-a"|"--apple" ) APPLE="$1"; shift;;
"-b"|"--banana" ) BANANA="$1"; shift;;
"-c"|"--cherry" ) CHERRY="$1"; shift;;
"-d"|"--dfruit" ) DFRUIT="$1"; shift;;
"-e"|"--eggplant" ) EGGPLANT="$1"; shift;;
"-f"|"--fig" ) FIG="$1"; shift;;
* ) echo "ERROR: Invalid option: \""$opt"\"" >&2
exit 1;;
esac
done
fi
if [[ "$APPLE" == "" || "$BANANA" == "" ]]; then
echo "ERROR: Options -a and -b require arguments." >&2
exit 1
fi
Thanks so much, everyone. This works perfectly so far.
: means "takes an argument", not "mandatory argument". That is, an option character not followed by : means a flag-style option (no argument), whereas an option character followed by : means an option with an argument.
Thus, you probably want
getopts "a:b:c:d:e:f:" opt
If you want "mandatory" options (a bit of an oxymoron), you can check after argument parsing that your mandatory option values were all set.
It isn't easy... Any "optional" option arguments must actually be required as far as getopts will know. Of course, an optional argument must be a part of the same argument to the script as the option it goes with. Otherwise an option -f with an optional argument and an option -a with a required argument can get confused:
# Is -a an option or an argument?
./script.sh -f -a foo
# -a is definitely an argument
./script.sh -f-a foo
The only way to do this is to test whether the option and its argument are in the same argument to the script. If so, OPTARG is the argument to the option. Otherwise, OPTIND must be decremented by one. Of course, the option is now required to have an argument, meaning a character will be found when an option is missing an argument. Just use another case to determine if any options are required:
while getopts ":a:b:c:d:e:f:" opt; do
case $opt in
a) APPLE="$OPTARG";;
b) BANANA="$OPTARG";;
c|d|e|f)
if test "$OPTARG" = "$(eval echo '$'$((OPTIND - 1)))"; then
OPTIND=$((OPTIND - 1))
else
case $opt in
c) CHERRY="$OPTARG";;
d) DFRUIT="$OPTARG";;
...
esac
fi ;;
\?) ... ;;
:)
case "$OPTARG" in
c|d|e|f) ;; # Ignore missing arguments
*) echo "option requires an argument -- $OPTARG" >&2 ;;
esac ;;
esac
done
This has worked for me so far.
For bash, this is my favorite way to parse/support cli args. I used getopts and it was too frustrating that it wouldn't support long options. I do like how it works otherwise - especially for built-in functionality.
usage()
{
echo "usage: $0 -OPT1 <opt1_arg> -OPT2"
}
while [ "`echo $1 | cut -c1`" = "-" ]
do
case "$1" in
-OPT1)
OPT1_ARGV=$2
OPT1_BOOL=1
shift 2
;;
-OPT2)
OPT2_BOOL=1
shift 1
;;
*)
usage
exit 1
;;
esac
done
Short, simple. An engineer's best friend!
I think this can be modified to support "--" options as well...
Cheers =)
Most shell getopts have been annoying me for a long time, including lack of support of optional arguments.
But if you are willing to use "--posix" style arguments, visit bash argument case for args in $#
Understanding bash's getopts
The bash manual page (quoting the version 4.1 manual) for getopts says:
getopts optstring name[args]
getopts is used by shell scripts to parse positional parameters. optstring contains
the option characters to be recognized; if a character is followed by a
colon, the option is expected to have an argument, which should be separated
from it by white space. The colon (‘:’) and question mark (‘?’) may not be
used as option characters. Each time it is invoked, getopts places the next
option in the shell variable name, initializing name if it does not exist, and the
index of the next argument to be processed into the variable OPTIND. OPTIND
is initialized to 1 each time the shell or a shell script is invoked. When an
option requires an argument, getopts places that argument into the variable
OPTARG. The shell does not reset OPTIND automatically; it must be manually
reset between multiple calls to getopts within the same shell invocation if a
new set of parameters is to be used.
When the end of options is encountered, getopts exits with a return value
greater than zero. OPTIND is set to the index of the first non-option argument,
and name is set to ‘?’.
getopts normally parses the positional parameters, but if more arguments are
given in args, getopts parses those instead.
getopts can report errors in two ways. If the first character of optstring is a
colon, silent error reporting is used. In normal operation diagnostic messages
are printed when invalid options or missing option arguments are encountered.
If the variable OPTERR is set to 0, no error messages will be displayed, even if
the first character of optstring is not a colon.
If an invalid option is seen, getopts places ‘?’ into name and, if not silent,
prints an error message and unsets OPTARG. If getopts is silent, the option
character found is placed in OPTARG and no diagnostic message is printed.
If a required argument is not found, and getopts is not silent, a question mark
(‘?’) is placed in name, OPTARG is unset, and a diagnostic message is printed. If
getopts is silent, then a colon (‘:’) is placed in name and OPTARG is set to the
option character found.
Note that:
The leading colon in the option string puts getopts into silent mode; it does not generate any error messages.
The description doesn't mention anything about optional option arguments.
I'm assuming that you are after functionality akin to:
script -ffilename
script -f
where the flag f (-f) optionally accepts an argument. This is not supported by bash's getopts command. The POSIX function getopt() barely supports that notation. In effect, only the last option on a command line can have an optional argument under POSIX.
What are the alternatives?
In part, consult Using getopts in bash shell script to get long and short command-line options.
The GNU getopt (singular!) program is a complex beastie that supports long and short options and supports optional arguments for long options (and uses GNU getopt(3). Tracking its source is entertaining; the link on the page at die.net is wrong; you'll find it in a sub-directory under ftp://ftp.kernel.org/pub/linux/utils/util-linux (without the -ng). I've not tracked down a location at http://www.gnu.org/ or http://www.fsf.org/ that contains it.
#!/bin/bash
while getopts ":a:b:c:d:e:f:" opt; do
case $opt in
a ) APPLE="$OPTARG";;
b ) BANANA="$OPTARG";;
c ) CHERRY="$OPTARG";;
d ) DFRUIT="$OPTARG";;
e ) EGGPLANT="$OPTARG";;
f ) FIG="$OPTARG";;
\?) echo "Invalid option: -"$OPTARG"" >&2
exit 1;;
: ) echo "Option -"$OPTARG" requires an argument." >&2
exit 1;;
esac
done
echo "Apple is "$APPLE""
echo "Banana is "$BANANA""
echo "Cherry is "$CHERRY""
echo "Dfruit is "$DFRUIT""
echo "Eggplant is "$EGGPLANT""
echo "Fig is "$FIG""
I already know about getopts, and this is fine, but it is annoying that you have to have a flag even for mandatory arguments.
Ideally, I'd like to be able to have a script which receives arguments in this form:
script.sh [optional arguments] [anything required]
for example
script.sh -rvx output_file.txt
where the script says you HAVE to have an output file. Is there any easy way to do this?
As far as I know, with getopts it would have to look like: script.sh -rvx -f output_file.txt, and that is just not very clean.
I can also use python if necessary, but only have 2.4 available, which is a bit dated.
Don't use the getopts builtin, use getopt(1) instead. They are (subtly) different and do different things well. For you scenario you could do this:
#!/bin/bash
eval set -- $(getopt -n $0 -o "-rvxl:" -- "$#")
declare r v x l
declare -a files
while [ $# -gt 0 ] ; do
case "$1" in
-r) r=1 ; shift ;;
-v) v=1 ; shift ;;
-x) x=1 ; shift ;;
-l) shift ; l="$1" ; shift ;;
--) shift ;;
-*) echo "bad option '$1'" ; exit 1 ;;
*) files=("${files[#]}" "$1") ; shift ;;
esac
done
if [ ${#files} -eq 0 ] ; then
echo output file required
exit 1
fi
[ ! -z "$r" ] && echo "r on"
[ ! -z "$v" ] && echo "v on"
[ ! -z "$x" ] && echo "x on"
[ ! -z "$l" ] && echo "l == $l"
echo "output file(s): ${files[#]}"
EDIT: for completeness I have provided an example of handling an option requiring an argument.
If you are using getops, just shift by $OPTIND-1 after your case statement. Then what is left in $* will be everything else, which is probably what you want.
shift $(( ${OPTIND} - 1 )); echo "${*}"
You're are suffering from illusions; using getopts does not require mandatory arguments prefixed by a flag letter. I tried to find a suitable example from my corpus of scripts; this is a semi-decent approximation. It is called rcsunco and is used to cancel a checkout from RCS. I haven't modified it in a while, I see; I use it quite often (because I haven't migrated from RCS completely, yet).
#!/bin/sh
#
# "#(#)$Id: rcsunco.sh,v 2.1 2002/08/03 07:41:00 jleffler Exp $"
#
# Cancel RCS checkout
# -V print version number
# -n do not remove or rename checked out file (like SCCS unget) (default)
# -r remove checked out file (default)
# -k keep checked out file as $file.keep
# -g checkout (unlocked) file after clean-up
# -q quiet checkout
: ${RCS:=rcs}
: ${CO:=co}
remove=yes
keep=no
get=no
quiet=
while getopts gknqrV opt
do
case $opt in
V) echo "`basename $0 .sh`: RCSUNCO Version $Revision: 2.1 $ ($Date: 2002/08/03 07:41:00 $)" |
rcsmunger
exit 0;;
g) get=yes;;
k) keep=yes;;
n) remove=no;;
q) quiet=-q;;
r) remove=yes;;
*) echo "Usage: `basename $0 .sh` [-{n|g}][-{r|k}] file [...]" 1>&2
exit 1;;
esac
done
shift $(($OPTIND-1))
for file in $*
do
rfile=$(rfile $file)
xfile=$(xfile $rfile)
if $RCS -u $rfile
then
if [ $keep = yes ]
then
if [ -f $xfile ]
then
mv $xfile $xfile.keep
echo "$xfile saved in $xfile.keep"
fi
elif [ $remove = yes ]
then rm -f $xfile
fi
if [ $get = yes ] && [ $remove = yes -o $keep = yes ]
then $CO $quiet $rfile
fi
fi
done
It's only a semi-decent approximation; the script quietly does nothing if you don't supply any file names after the optional arguments. However, if you need to, you can check that the mandatory arguments are present after the 'shift'. Another script of mine does have mandatory arguments. It contains:
...
shift $(($OPTIND - 1))
case $# in
2) case $1 in
install) MODE=Installation;;
uninstall) MODE=Uninstallation;;
*) usage;;
esac;;
*) usage;;
esac
So, that command (jlss) can take optional arguments such as -d $HOME, but requires either install or uninstall followed by the name of something to install. The basic mode of use is:
jlss install program
But the optional mode is:
jlss -d $HOME -u me -g mine -x -p install program
I didn't show all of jlss because it has about 12 options - it isn't as compact as rcsunco.
If you were dealing with mandatory arguments before option arguments, then you'd have to do a bit more work:
You'd pick up the mandatory arguments, shifting them out of the way.
Then you process the optional arguments with the flags.
Finally, if appropriate, you handle the extra 'file name' arguments.
If you are dealing with mandatory arguments interspersed with option arguments (both before and after the mandatory ones), then you have still more work to do. This is used by many VCS systems; CVS and GIT both have the facility:
git -global option command [-sub option] [...]
Here, you run one getopts loop to get the global options; pick up the mandatory arguments; and run a second getopts loop to get the sub-options (and maybe run a final loop over the 'file name' arguments).
Isn't life fun?
And I heard a completely opposite thing, that you shouldn't use getopt, but the getopts builtin.
Cross-platform getopt for a shell script
Never use getopt(1). getopt cannot handle empty arguments strings, or
arguments with embedded whitespace. Please forget that it ever
existed.
The POSIX shell (and others) offer getopts which is safe to use
instead.
Here's yet another way to "Option-ize your shell scripts" (whithout using getopt or getopts):
http://bsdpants.blogspot.com/2007/02/option-ize-your-shell-scripts.html