Is it possible to implement sub-commands for bash scripts. I have something like this in mind:
http://docs.python.org/dev/library/argparse.html#sub-commands
Here's a simple unsafe technique:
#!/bin/bash
clean() {
echo rm -fR .
echo Thanks to koola, I let you off this time,
echo but you really shouldn\'t run random code you download from the net.
}
help() {
echo Whatever you do, don\'t use clean
}
args() {
printf "%s" options:
while getopts a:b:c:d:e:f:g:h:i:j:k:l:m:n:o:p:q:r:s:t:u:v:w:x:y:z: OPTION "$#"; do
printf " -%s '%s'" $OPTION $OPTARG
done
shift $((OPTIND - 1))
printf "arg: '%s'" "$#"
echo
}
"$#"
That's all very cool, but it doesn't limit what a subcommand could be. So you might want to replace the last line with:
if [[ $1 =~ ^(clean|help|args)$ ]]; then
"$#"
else
echo "Invalid subcommand $1" >&2
exit 1
fi
Some systems let you put "global" options before the subcommand. You can put a getopts loop before the subcommand execution if you want to. Remember to shift before you fall into the subcommand execution; also, reset OPTIND to 1 so that the subcommands getopts doesn't get confused.
Related
How do I parse the second argument into a variable using bash and getopt on the following script.
I can do sh test.sh -u and get "userENT" to display. But if I do sh test.sh -u testuser on this script I get an error.
#!/bin/sh
# Now check for arguments
OPTS=`getopt -o upbdhrstv: --long username,password,docker-build,help,version,\
release,remote-registry,stage,develop,target: -n 'parse-options' -- "$#"`
while true; do
case "$1" in
-u | --username)
case "$2" in
*) API_KEY_ART_USER="$2"; echo "userENT" ;shift ;;
esac ;;
-- ) shift; break ;;
* ) if [ _$1 != "_" ]; then ERROR=true; echo; echo "Invalid option $1"; fi; break ;;
esac
done
echo "user" $API_KEY_ART_USER
How can I pass the -u testuser and not have an Invalid option testuser error?
Output:
>sh test3.sh -u testuser
userENT
Invalid option testuser
user testuser
man getopt would tell you that a colon following the option indicates that it has an argument. You only have a colon after the v. You also weren't shifting within your loop, so you'd be unable to parse any options past the first one. And I'm not sure why you felt the need to have a second case statement that only had a single default option. In addition, there were a number of poor practices in your code including use of all caps variable names and backticks instead of $() for executing commands. And you've tagged your question bash but your shebang is /bin/sh. Give this a try, but you shouldn't be using code without understanding what it does.
#!/bin/sh
# Now check for arguments
opts=$(getopt -o u:pbdhrstv: --long username:,password,docker-build,help,version,\
release,remote-registry,stage,develop,target: -n 'parse-options' -- "$#")
while true; do
case "$1" in
-u|--username)
shift
api_key_art_user="$1"
echo "userENT"
;;
--)
shift;
break
;;
*)
if [ -n "$1" ]; then
err=true
echo "Invalid option $1"
fi
break
;;
esac
shift
done
echo "user $api_key_art_user"
Let's say I have a bunch of if statements with the form:
if (some flag variable/argument is set) then
execute another command or bash script
This is a bit troublesome to maintain, so I was wondering if there was some other way of doing this. While this guide is for node.js, I was wondering if it is possible to achieve something similar in bash
I wonder if you're looking for something like this:
#!/bin/bash
# initialize global options
debug=false
verbose=0
main() {
local OPTIND
while getopts :hdv: opt; do
case $opt in
h) show_help; exit ;;
d) debug=true ;;
v) verbose=$OPTARG;;
:) echo "error: missing argument for -$OPTARG"; exit 1;;
?) echo "error: unknown option -$OPTARG"; exit 1 ;;
esac
done
shift $((OPTIND-1))
if [[ -z $1 ]]; then
echo "error: missing subcommand"
show_help
exit 1
fi
case $1 in
bar|baz)
# invoke the command with the arguments
"$#" ;;
*) echo "error: unknown subcommand $1"; exit 1;;
esac
}
show_help() {
echo "usage: $(basename "$0") [global opts] subcommand [local opts and args]"
echo "... more details..."
}
bar() {
echo "you called $FUNCNAME with args $*"
}
baz() {
echo "this is baz"
local OPTIND
while getopts :ab opt; do
case $opt in
a|b) echo "you selected option $opt";;
?) echo "unknown option -$OPTARG";;
esac
done
if $debug; then echo "some debug message"; fi
(( verbose > 0 )) && echo "some verbose message"
}
main "$#"
You could write a wrapper function that checks the variable and then executes the command passed in:
#!/bin/bash
run_if_set() {
local var=$1
shift
(($# == 0)) && return # nothing to run
[[ $var ]] && "$#" # execute only if var is set to a non-empty string
}
Then replace your if statements with:
run_if_set "$var" command ...
which is slightly more readable than
if [[ $var ]]; then
command ...
fi
or
[[ $var ]] && command ...
This question already has an answer here:
Storing bash script argument with multiple values
(1 answer)
Closed 5 years ago.
I have been researching on using bash scripts to process command-line arguments. I have multiple optional arguments, each of which have one or more operands. An example is:
./script.sh -f file1 file2 -s server1 server2
-f itself is optional, but must be followed by filename; -s is optional, can be used without any operands or operands.
I know I can force putting "" on operands so I only deal with arguments with one operand and can use case $1 $2 shift to process it.
But I am interested in doing so without quotes, just to save some typing for the users.
A rough idea would be read in "$#" as one string, and separate them by space, then locate arguments with -/-- and assign operands following them. Maybe I can use an array to do that?
Any suggestions would be welcome.
Thanks folks for your wonderful suggestions. After spending some more time I resolved to the solution below:
Simply put, I use case and few checks to determine if the argument is an option or not. I use only alter flag variables during argument processing and then use the flags to determine what functions I will perform. In a way that I can have options in different order.
main(){
# flags, 1 is false, 0 is true. it's the damn bash LOCAL_DEPLOY=1
SERVER_DEPLOY=1 DRY_RUN=0
FILES=("${ALLOWEDFILES[#]}");
DEPLOYTARGET=("${ALLOWEDSERVERS[#]}");
if [ $# -eq 0 ]
then
printf -- "Missing optins, perform DRY RUN\nFor help, run with -h/--help\n"
for target in "${FILES[#]}"; do generate "$target"; done
echo "....dry run: markdown files generated in rendered/"
exit 0
fi
while true ; do
case "$1" in
-f |--file) # required operands
case "$2" in
"") die $1 ;;
*)
FILES=($2)
for i in "${FILES[#]}"; do
if is_option $i; then die $1; fi # check for option
if ! check_allowed $i ${ALLOWEDFILES[#]}; then exit 1; fi
done;
shift 2;; # input FILES are good
esac ;;
-l|--local) # no operands expected
DRY_RUN=1 # turn off dryrun
LOCAL_DEPLOY=0 # turn on local deploy
shift ;;
-s|--server) # optional operands
case "$2" in
"") shift ;;
*)
DEPLOYTARGET=($2) # use input
for i in "${DEPLOYTARGET[#]}"; do
if is_option $i; then die $1; fi # check for option
if ! check_allowed $i ${ALLOWEDSERVERS[#]}; then exit 1; fi
done ; shift 2;; # use input value
esac
DRY_RUN=1
SERVER_DEPLOY=0
;;
-n|--dryrun) # dry-run:generate markdown files only
DRY_RUN=0
shift ;;
-h|--help) # docs
print_help
exit 0
;;
--) shift; break ;;
-?*)
printf 'ERROR: Unkown option: %s\nExisting\n\n' "$1" >&2
print_help
exit 1
shift
;;
*)
break ;;
esac
done
echo "choose files: ${FILES[#]}"
echo ""
# dry-run
if [ $DRY_RUN == 0 ]; then
echo "..perform dry run.."
for target in "${FILES[#]}"; do generate "$target"; done
echo "....dry run: markdown files generated in rendered/"
exit 0
fi
# local-deploy
if [ $LOCAL_DEPLOY == 0 ] && [ $SERVER_DEPLOY != 0 ]; then
echo "..deploy locally"
for target in "${FILES[#]}"; do
generate "$target" > /dev/null
deploylocal "$target"
done;
# sync hexo-gcs hexo-yby
cd "$(dirname $HEXOLOCATION)"
./syncRepo.sh
printf -- "....hexo-gcs hexo-yby synced\n"
cd $CURRENTLOCATION
fi
# server-deploy
if [ $SERVER_DEPLOY == 0 ]; then
echo "..deploy on servers: ${DEPLOYTARGET[#]}"
echo ""
for target in "${FILES[#]}"; do # deploy locally
generate "$target" > /dev/null
deploylocal "$target"
done
# sync hexo-gcs hexo-yby
cd "$(dirname $HEXOLOCATION)"
./syncRepo.sh
printf -- "....hexo-gcs hexo-yby synced\n"
cd $CURRENTLOCATION
# deploy to selected server: git or gcp
for dt in "${DEPLOYTARGET[#]}"; do
deployserver $dt
done
fi
}
I am trying to write a bash script that takes in an option.
Lets call these options A and B.
In the script A and B may or may not be defined as variables.
I want to be able to check if the variable is defined or not.
I have tried the following but it doesn't work.
if [ ! -n $1 ]; then
echo "Error"
fi
Thanks
The "correct" way to test whether a variable is set is to use the + expansion option. You'll see this a lot in configure scripts:
if test -s "${foo+set}"
where ${foo+set} expands to "set" if it is set or "" if it's not. This allows for the variable to be set but empty, if you need it. ${foo:+set} additionally requires $foo to not be empty.
(That $(eval echo $a) thing has problems: it's slow, and it's vulnerable to code injection (!).)
Oh, and if you just want to throw an error if something required isn't set, you can just refer to the variable as ${foo:?} (leave off the : if set but empty is permissible), or for a custom error message ${foo:?Please specify a foo.}.
You did not define how these options should be passed in, but I think:
if [ -z "$1" ]; then
echo "Error"
exit 1
fi
is what you are looking for.
However, if some of these options are, err, optional, then you might want something like:
#!/bin/bash
USAGE="$0: [-a] [--alpha] [-b type] [--beta file] [-g|--gamma] args..."
ARGS=`POSIXLY_CORRECT=1 getopt -n "$0" -s bash -o ab:g -l alpha,beta:,gamma -- "$#"`
if [ $? -ne 0 ]
then
echo "$USAGE" >&2
exit 1
fi
eval set -- "$ARGS"
unset ARGS
while true
do
case "$1" in
-a) echo "Option a"; shift;;
--alpha) echo "Option alpha"; shift;;
-b) echo "Option b, arg '$2'"; shift 2;;
--beta) echo "Option beta, arg '$2'"; shift 2;;
-g|--gamma) echo "Option g or gamma"; shift;;
--) shift ; break ;;
*) echo "Internal error!" ; exit 1 ;;
esac
done
echo Remaining args
for arg in "$#"
do
echo '--> '"\`$arg'"
done
exit 0
Don't do it that way, try this:
if [[ -z $1 ]]; then
echo "Error"
fi
The error in your version is actually the lack of quoting.
Should be:
if [ ! -n "$1" ]; then
echo "Error"
fi
But you don't need the negation, use -z instead.
If you work on Bash, then use double brackets [[ ]] too.
from the man bash page:
-z string
True if the length of string is zero.
-n string
True if the length of string is non-zero.
Also, if you use bash v4 or greater (bash --version) there's -v
-v varname
True if the shell variable varname is set (has been assigned a value).
The trick is "$1", i.e.
root#root:~# cat auto.sh
Usage () {
echo "error"
}
if [ ! -n $1 ];then
Usage
exit 1
fi
root#root:~# bash auto.sh
root#root:~# cat auto2.sh
Usage () {
echo "error"
}
if [ ! -n "$1" ];then
Usage
exit 1
fi
root#root:~# bash auto2.sh
error
I want the user to input something at the command line either -l or -e.
so e.g. $./report.sh -e
I want an if statement to split up whatever decision they make so i have tried...
if [$1=="-e"]; echo "-e"; else; echo "-l"; fi
obviously doesn't work though
Thanks
I use:
if [[ "$1" == "-e" ]]; then
echo "-e"
else
echo "-l";
fi
However, for parsing arguments, getopts might make your life easier:
while getopts "el" OPTION
do
case $OPTION in
e)
echo "-e"
;;
l)
echo "-l"
;;
esac
done
If you want it all on one line (usually it makes it hard to read):
if [ "$1" = "-e" ]; then echo "-e"; else echo "-l"; fi
You need spaces between the square brackets and what goes inside them. Also, just use a single =. You also need a then.
if [ $1 = "-e" ]
then
echo "-e"
else
echo "-l"
fi
The problem specific to -e however is that it has a special meaning in echo, so you are unlikely to get anything back. If you try echo -e you'll see nothing print out, while echo -d and echo -f do what you would expect. Put a space next to it, or enclose it in brackets, or have some other way of making it not exactly -e when sending to echo.
If you just want to print which parameter the user has submitted, you can simply use echo "$1". If you want to fall back to a default value if the user hasn't submitted anything, you can use echo "${1:--l} (:- is the Bash syntax for default values). However, if you want really powerful and flexible argument handling, you could look into getopt:
params=$(getopt --options f:v --longoptions foo:,verbose --name "my_script.sh" -- "$#")
if [ $? -ne 0 ]
then
echo "getopt failed"
exit 1
fi
eval set -- "$params"
while true
do
case $1 in
-f|--foo)
foobar="$2"
shift 2
;;
-v|--verbose)
verbose='--verbose'
shift
;;
--)
while [ -n "$3" ]
do
targets[${#targets[*]}]="$2"
shift
done
source_dir=$(readlink -fn -- "$2")
shift 2
break
;;
*)
echo "Unhandled parameter $1"
exit 1
;;
esac
done
if [ $# -ne 0 ]
then
error "Extraneous parameters." "$help_info" $EX_USAGE
fi