Execute bash script from URL

Question

Say I have a file at the URL http://mywebsite.example/myscript.txt that contains a script:

#!/bin/bash
echo "Hello, world!"
read -p "What is your name? " name
echo "Hello, ${name}!"

And I'd like to run this script without first saving it to a file. How do I do this?

Now, I've seen the syntax:

bash < <(curl -s http://mywebsite.example/myscript.txt)

But this doesn't seem to work like it would if I saved to a file and then executed. For example readline doesn't work, and the output is just:

$ bash < <(curl -s http://mywebsite.example/myscript.txt)
Hello, world!

Similarly, I've tried:

curl -s http://mywebsite.example/myscript.txt | bash -s --

With the same results.

Originally I had a solution like:

timestamp=`date +%Y%m%d%H%M%S`
curl -s http://mywebsite.example/myscript.txt -o /tmp/.myscript.${timestamp}.tmp
bash /tmp/.myscript.${timestamp}.tmp
rm -f /tmp/.myscript.${timestamp}.tmp

But this seems sloppy, and I'd like a more elegant solution.

I'm aware of the security issues regarding running a shell script from a URL, but let's ignore all of that for right now.

If you do end up creating a temporary file, you should probably be using `mktemp` instead of rolling your own solution — Hasturkun, Apr 20 '11 at 19:44

score 292 · Accepted Answer · edited Jun 23 '22 at 19:50

292

source <(curl -s http://mywebsite.example/myscript.txt)

ought to do it. Alternately, leave off the initial redirection on yours, which is redirecting standard input; bash takes a filename to execute just fine without redirection, and <(command) syntax provides a path.

bash <(curl -s http://mywebsite.example/myscript.txt)

It may be clearer if you look at the output of echo <(cat /dev/null)

edited Jun 23 '22 at 19:50

Stephen Ostermiller

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answered Apr 20 '11 at 19:45

geekosaur

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Thanks, this made it clear what was going on. Just curious, what is the advantage of using that initial redirection? I ask because for RVM installation, they use the command: `bash < <(curl -s https://rvm.beginrescueend.com/install/rvm)` Why not just: `bash <(curl -s https://rvm.beginrescueend.com/install/rvm)` – Tristan Apr 20 '11 at 20:49
@Tristan: If they're running an interactive install script/program (commercial installer package, or an installer whuch also supports custom installation types), they can provide it default answers. – geekosaur Apr 20 '11 at 20:52
4

Small note: if wget is available but curl is not (e.g. on a stock Ubuntu desktop system), you can substitute `wget -q http://mywebsite.com/myscript.txt -O -` for `curl -s http://mywebsite.com/myscript.txt`). – Chiara Coetzee Aug 21 '12 at 22:47
7

Be aware that you can't pass command line arguments to your script. `bash will_not_work foobar <(curl -s http://example.com/myscript.sh)` If you own the script you can use environment variables instead like so: `MYFLAG1=will_work bash MYFLAG2=foobar <(curl -s http://example.com/myscript.sh)` and it also works with pipes like so: `curl -s http://example.com/myscript.sh | MYFLAG1=will_work MYFLAG2=foobar bash` This of course requires that you use MYFLAG1 and MYFLAG2 instead of $1 and $2 – Bruno Bronosky Mar 18 '13 at 18:07
5

$ sudo bash <(curl -s http://xxx) got error: bash: /dev/fd/63: Bad file descriptor – Yin Nov 09 '15 at 06:49
@Jake Just a guess, but can it be that you are running `bash` as root, but 'curl' as a standard user? I'm not sure if Linux splits up file descriptors based on user, or at least restricts them to the user that created them. – IQAndreas Nov 17 '15 at 09:25
@Jake Try running `su`, then while you are root, run the command without `sudo`. – IQAndreas Nov 17 '15 at 09:25
If the script you're downloading needs to change environment variables like the path, this won't work. Is there a way to do this that allows changing the environment variables in the executing environment? – B T Nov 17 '15 at 09:41
3

The first solution (the one using source) did not work at all. The second worked somewhat but has its limitations. It is executing the script from the URL in a subshell. I have some functions defined in the script that I would like to use in the parent. Is there anyway to achieve that? Or am I out of luck and the only solution is to copy that script in a temporary file and then source it? – Harsh Pandey Sep 16 '17 at 00:19
How can you send arguments to a file executed this way? – Camilo Sampedro Oct 18 '18 at 07:51
The source version affects the current session, which means if your remote script calls `exit` (e.g. for an error) then it will drop you out of your session. The bash version works better for this, and also allows environment variables to be set locally in the script without persisting. – Richard Oct 08 '19 at 08:16

score 113 · Answer 2 · answered Jul 13 '13 at 20:40

113

This is the way to execute remote script with passing to it some arguments (arg1 arg2):

curl -s http://server/path/script.sh | bash /dev/stdin arg1 arg2

answered Jul 13 '13 at 20:40

Anandi Das

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this breaks stty :\ use `bash <(curl ... ) ` if you use stdin – Flores Robles Jan 15 '16 at 10:04

user77115 · Answer 3 · 2019-07-26T11:21:51.307

74

For bash, Bourne shell and fish:

curl -s http://server/path/script.sh | bash -s arg1 arg2

Flag "-s" makes shell read from stdin.

edited Jul 26 '19 at 11:21

answered Mar 28 '15 at 12:03

user77115

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2

this should work in most shells, while the accepted answer does not work with *fish*, for example. – hoijui Jun 10 '19 at 11:36
1

What is `arg1 arg2`?. Can I call just `curl -s http://server/path/script.sh | bash -s`? – Nairum Jan 08 '21 at 17:42
@Nairum Yes, you can call without arg1 and arg2, which are parameters passed to script.sh. If script.sh requires parameters to be able to execute, you can add as many parameters as you like. Having 2 parameters is just an example. – user77115 Mar 15 '21 at 07:39

score 21 · Answer 4 · edited Aug 30 '18 at 19:33

21

Use:

curl -s -L URL_TO_SCRIPT_HERE | bash

For example:

curl -s -L http://bitly/10hA8iC | bash

edited Aug 30 '18 at 19:33

Bonifacio2

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answered May 25 '16 at 10:29

Katie MC

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score 16 · Answer 5 · edited Jun 23 '22 at 19:51

16

Using wget, which is usually part of default system installation:

bash <(wget -qO- http://mywebsite.example/myscript.txt)

edited Jun 23 '22 at 19:51

Stephen Ostermiller

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answered May 16 '13 at 09:48

amra

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RTFM: https://www.gnu.org/software/wget/manual/wget.html. ||| -q == --quiet == "Turn off Wget’s output." ||| -O- == --output-document=- == If ‘-’ is used as file, documents will be printed to standard output. – amra Nov 20 '17 at 11:26

score 13 · Answer 6 · answered Jul 09 '13 at 18:52

13

You can also do this:

wget -O - https://raw.github.com/luismartingil/commands/master/101_remote2local_wireshark.sh | bash

answered Jul 09 '13 at 18:52

luismartingil

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score 12 · Answer 7 · edited Jun 23 '22 at 19:52

I often using the following is enough

curl -s http://mywebsite.example/myscript.txt | sh

But in a old system( kernel2.4 ), it encounter problems, and do the following can solve it, I tried many others, only the following works

curl -s http://mywebsite.example/myscript.txt -o a.sh && sh a.sh && rm -f a.sh

Examples

$ curl -s someurl | sh
Starting to insert crontab
sh: _name}.sh: command not found
sh: line 208: syntax error near unexpected token `then'
sh: line 208: ` -eq 0 ]]; then'
$

The problem may cause by network slow, or bash version too old that can't handle network slow gracefully

However, the following solves the problem

$ curl -s someurl -o a.sh && sh a.sh && rm -f a.sh
Starting to insert crontab
Insert crontab entry is ok.
Insert crontab is done.
okay
$

score 12 · Answer 8 · answered Sep 20 '16 at 09:24

12

The best way to do it is

curl http://domain/path/to/script.sh | bash -s arg1 arg2

which is a slight change of answer by @user77115

answered Sep 20 '16 at 09:24

Vamsidhar Muggulla

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score 12 · Answer 9 · edited Jun 23 '22 at 19:52

12

You can use curl and send it to bash like this:

bash <(curl -s http://mywebsite.example/myscript.txt)

edited Jun 23 '22 at 19:52

Stephen Ostermiller

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answered Apr 20 '11 at 19:42

Random832

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score 8 · Answer 10 · answered Feb 13 '15 at 13:54

8

Also:

curl -sL https://.... | sudo bash -

answered Feb 13 '15 at 13:54

Thomas Decaux

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5

What dose the last strip mean? – towry Feb 23 '15 at 07:59
2

From the bash man page: A -- signals the end of options and disables further option processing. Any arguments after the -- are treated as filenames and arguments. An argument of - is equivalent to --. – Mingjiang Shi Jun 30 '15 at 08:59

score 4 · Answer 11 · answered Oct 21 '15 at 05:13

4

Just combining amra and user77115's answers:

wget -qO- https://raw.githubusercontent.com/lingtalfi/TheScientist/master/_bb_autoload/bbstart.sh | bash -s -- -v -v

It executes the bbstart.sh distant script passing it the -v -v options.

answered Oct 21 '15 at 05:13

ling

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score 2 · Answer 12 · answered Jul 25 '18 at 21:23

Is some unattended scripts I use the following command:

sh -c "$(curl -fsSL <URL>)"

I recommend to avoid executing scripts directly from URLs. You should be sure the URL is safe and check the content of the script before executing, you can use a SHA256 checksum to validate the file before executing.

score 2 · Answer 13 · answered Jan 02 '22 at 02:40

2

instead of executing the script directly, first download it and then execute

SOURCE='https://gist.githubusercontent.com/cci-emciftci/123123/raw/123123/sample.sh'

curl $SOURCE -o ./my_sample.sh
chmod +x my_sample.sh
./my_sample.sh

answered Jan 02 '22 at 02:40

emrcftci

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score 1 · Answer 14 · answered Apr 13 '18 at 02:06

This way is good and conventional:

17:04:59@itqx|~
qx>source <(curl -Ls http://192.168.80.154/cent74/just4Test) Lord Jesus Loves YOU
Remote script test...
Param size: 4

---------
17:19:31@node7|/var/www/html/cent74
arch>cat just4Test
echo Remote script test...
echo Param size: $#

score 1 · Answer 15 · edited Jun 23 '22 at 19:52

If you want the script run using the current shell, regardless of what it is, use:

${SHELL:-sh} -c "$(wget -qO - http://mywebsite.example/myscript.txt)"

if you have wget, or:

${SHELL:-sh} -c "$(curl -Ls http://mywebsite.example/myscript.txt)"

if you have curl.

This command will still work if the script is interactive, i.e., it asks the user for input.

Note: OpenWRT has a wget clone but not curl, by default.

score -4 · Answer 16 · edited Dec 15 '18 at 22:34

-4

bash | curl http://your.url.here/script.txt

actual example:

juan@juan-MS-7808:~$ bash | curl https://raw.githubusercontent.com/JPHACKER2k18/markwe/master/testapp.sh


Oh, wow im alive


juan@juan-MS-7808:~$

edited Dec 15 '18 at 22:34

Stephen Kennedy

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answered Dec 15 '18 at 22:32

Random memes 2k18

1

This is straight up wrong. Test your scripts before posting and don't fake output. – korkman Apr 18 '20 at 19:49

Execute bash script from URL

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