How to require command line parameters in bash? - bash

Question

I have a bash script where I need to have some parameters. Usage should be only between:
./script.sh --scan [scan type] [keyword]
or
./script.sh --help
In example it should be something like this:
$ ./script.sh
[Usage]
$ ./script.sh --scan
Specify scan type
$ ./script.sh --help --scan
[Usage]
$ ./script.sh --scan short
Specify keyword to search
$ ./script.sh --scan short keyword
[Starts short scanning for "keyword" - go to function where my script is, blah, blah]
$ ./script.sh keyword --scan short
[As above]
$ ./script.sh keyword
[Usage]
How I can achieve this?

Answer 1

This is just off the top of my head:
if [ "$1" = "--scan" ] ; then
if [ "$#" -ge 2 ] ; then
_SCANTYPE=$2
if [ "$#" -ge 3 ] ; then
_KEYWORD=$3
else
echo -n "Specify keyword to search: "
read _KEYWORD
fi
else
echo -n "Specify scan type: "
read _SCANTYPE
echo -n "Specify keyword to search: "
read _KEYWORD
fi
# Actual scan code
else
# Display usage info
fi
This is pretty basic, of course, but hopefully it will get you started.

Answer 2

Almost any Configure script to build a piece of software from source will have what you want. From perl's:
: option parsing
while test $# -gt 0; do
case "$1" in
-d) shift; fastread=yes;;
-e) shift; alldone=cont;;
-f)
shift
cd ..
if test -r "$1"; then
config_sh="$1"
else
echo "$me: cannot read config file $1." >&2
error=true
fi
cd UU
shift;;
--help|\
-h) shift; error=true;;
-r) shift; reuseval=true;;
-s) shift; silent=true; realsilent=true;;
-E) shift; alldone=exit;;
-K) shift; knowitall=true;;
-O) shift; override=true;;
-S) shift; silent=true; extractsh=true;;
-D)
shift
case "$1" in
*=)
echo "$me: use '-U symbol=', not '-D symbol='." >&2
echo "$me: ignoring -D $1" >&2
;;
*=*) echo "$1" | \
sed -e "s/'/'\"'\"'/g" -e "s/=\(.*\)/='\1'/" >> optdef.sh;;
*) echo "$1='define'" >> optdef.sh;;
esac
shift
;;
-U)
shift
case "$1" in
*=) echo "$1" >> optdef.sh;;
*=*)
echo "$me: use '-D symbol=val', not '-U symbol=val'." >&2
echo "$me: ignoring -U $1" >&2
;;
*) echo "$1='undef'" >> optdef.sh;;
esac
shift
;;
-A)
shift
xxx=''
yyy="$1"
zzz=''
uuu=undef
case "$yyy" in
*=*) zzz=`echo "$yyy"|sed 's!=.*!!'`
case "$zzz" in
*:*) zzz='' ;;
*) xxx=append
zzz=" "`echo "$yyy"|sed 's!^[^=]*=!!'`
yyy=`echo "$yyy"|sed 's!=.*!!'` ;;
esac
;;
esac
case "$xxx" in
'') case "$yyy" in
*:*) xxx=`echo "$yyy"|sed 's!:.*!!'`
yyy=`echo "$yyy"|sed 's!^[^:]*:!!'`
zzz=`echo "$yyy"|sed 's!^[^=]*=!!'`
yyy=`echo "$yyy"|sed 's!=.*!!'` ;;
*) xxx=`echo "$yyy"|sed 's!:.*!!'`
yyy=`echo "$yyy"|sed 's!^[^:]*:!!'` ;;
esac
;;
esac
case "$xxx" in
append)
echo "$yyy=\"\${$yyy}$zzz\"" >> posthint.sh ;;
clear)
echo "$yyy=''" >> posthint.sh ;;
define)
case "$zzz" in
'') zzz=define ;;
esac
echo "$yyy='$zzz'" >> posthint.sh ;;
eval)
echo "eval \"$yyy=$zzz\"" >> posthint.sh ;;
prepend)
echo "$yyy=\"$zzz\${$yyy}\"" >> posthint.sh ;;
undef)
case "$zzz" in
'') zzz="$uuu" ;;
esac
echo "$yyy=$zzz" >> posthint.sh ;;
*) echo "$me: unknown -A command '$xxx', ignoring -A $1" >&2 ;;
esac
shift
;;
-V) echo "$me generated by metaconfig 3.5 PL0." >&2
exit 0;;
--) break;;
-*) echo "$me: unknown option $1" >&2; shift; error=true;;
*) break;;
esac
done

Answer 3

For your two examples
./script.sh --scan [scan type] [keyword]
or
./script.sh --help
Try this
#!/bin/bash
usageMsg="usage:ScriptName --scan [scan type] [keyword] OR --help"
case $# in
[123] ) : nothing_may_be_OK ;;
0 ) # no args, display usageMsg
echo "$usageMsg" >&2 ; exit 1 ;;
esac
case "$1" in
--[Hh][Ee][Ll][Pp] ) echo "$usageMsg" >&2 ; exit 1 ;;
--[Ss][Cc][Aa][Nn] )
shift
case $# in
0) # using defaults
scanType="PrimaryScan" # change to your default scanType
keyword="PrimaryKeyWord" # again, change to your default value
;;
1)
echo "$usageMsg" >&2
echo "must provide both [scan type] and [keyword] arguments. Cant continue" >&2
exit 1
;;
2)
scanType="$1"
keyword="$2"
;;
esac # case $#
;;
esac # case $1
#restof your code goes here
echo "running scanner with scanType=$scanType and keyWord=$keyword"
echo ". . . . ."
exit 0
I'm guessing that your usage pattern means --scan OR advanced scan (with details), i.e. --scan [scan type] [keyword]
If you really intend for user to optionally add [scan type] AND/OR [keyword] then you'll need some further use of the techniques in the code above.
IHTH

Answer 4

I finally managed that! The basic version is:
#!/bin/bash
function usage
{
echo "Usage: usage"
exit
}
while [ $# -gt 0 ]; do
case $1 in
-h|--help)
usage
;;
-s|--scan)
scantype="$2"
shift
;;
-*)
usage
;;
*)
keyword="$1"
;;
esac
shift
done
if [ -z "$scantype" ]; then
echo "no scantype"
exit
fi
if [[ "$scantype" != "full" && "$scantype" != "long" && "$scantype" != "extended" && "$scantype" != "short" ]]; then
echo "invalid scantype"
exit
fi
if [ -z "$keyword" ]; then
echo "nokeyword"
exit
fi
echo "scantype: $scantype"
echo "keyword: $keyword"
Anyway thanks for your help :)