Use Bash with script text from stdin and options from command line

Question

I want to use /bin/bash (possibly /bin/sh) with the option -f passed to, and handled by, the script. Precisely,

while getopts f OPT
do
  case $OPT in
    "f" ) readonly FLG_F="TRUE" 
   esac
done

if [ $FLG_F ]; then
  rm -rf $KIBRARY_DIR
fi

and when these lines are in a file http://hoge.com/hoge.sh,

I can do this, for instance,

wget http://hoge.com/hoge.sh
/bin/bash hoge.sh -f

but not

/bin/bash -f hoge.sh

I know the reason but I want to do like this,

wget -O - http://hoge.com/hoge.sh | /bin/bash

with -f option for hoge.sh not for /bin/bash

Are there any good ways to do this?

/bin/bash <(wget -O - http://hoge.com/hoge.sh) -f

worked. but this is only for bash users, right?

BTW, you've got some quoting bugs here -- try running your code through shellcheck.net — Charles Duffy
– Charles Duffy, Commented Jul 26, 2016 at 3:24
Also, -f is not the only way to set FLG_F; the value can be inherited from the environment. Try FLG_F=TRUE bash hoge.sh. You'll want to clear the value of FLG_F at the top of your script before you check for the -f option. — chepner
– chepner, Commented Jul 26, 2016 at 12:18
Running a shell script directly from a 3rd party is a bad idea; download it, verify that it will do what you expect, then run it. — chepner
– chepner, Commented Jul 26, 2016 at 12:21
...and certainly not over plain http; if you don't use SSL, you don't know it's really coming from where you think it is. It really ain't that hard to set up a mutating inline proxy -- heck, I was doing that as part of an April Fool joke almost 20 years ago. Trusting the people you're downloading code from not to have been hacked isn't wise either -- this is why robust software packaging systems (and DSCMs intended to be securable) have support for OpenPGP signatures. — Charles Duffy
– Charles Duffy, Commented Jul 26, 2016 at 12:22

Diego Torres Milano · Accepted Answer · 2016-07-26 03:21:02Z

4

Using bash you can do

wget -O - http://hoge.com/hoge.sh | /bin/bash -s -- -f

as with -s commands are read from the standard input. This option allows the positional parameters to be set too. It should work with other POSIX shells too.

answered Jul 26, 2016 at 3:21

Diego Torres Milano

69.9k9 gold badges116 silver badges145 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

kensuke1984 Over a year ago

It worked. Thank you very much you also considered POSIX Im taking care of.. appreciate it..

chepner Over a year ago

This is a bad idea for different reasons; you don't know what you are getting from hoge.com before you execute it.

Collectives™ on Stack Overflow

Use Bash with script text from stdin and options from command line

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related