curl command not executing via shell script in bash

linux bash shell curl gnome-terminal

51,918

Solution 1

A command embedded within a parenthesis runs as a sub-shell so your environment variables will be missing.

Try eval:

curlCmd="curl 'https://www.facebook.com/vivekkumar27june88' > ~/Desktop/fb.html"
eval $curlCmd

Solution 2

Create your script t.sh as this single line only:

curl -k "https://www.facebook.com/vivekkumar27june88" -o ~/Desktop/fb.html

As per man curl:

-k, --insecure

(SSL) This option explicitly allows curl to perform "insecure" SSL connections transfers.  
All  SSL  connections  are  attempted  to be made secure by using the CA certificate bundle
installed by default. This makes all connections considered "insecure" fail unless -k,
--insecure is used.

-o file

Store output in the given filename.

Solution 3

As @Chepner said, go read BashFAQ #50: I'm trying to put a command in a variable, but the complex cases always fail!. To summarize, how you should do things like this depends on what your goal is.

If you don't need to store the command, don't! Storing commands is difficult to get right, so if you don't need to, just skip that mess and execute it directly:
```
curl "https://www.facebook.com/vivekkumar27june88" > ~/Desktop/fb.html
```
If you want to hide the details of the command, or are going to use it a lot and don't want to write it out each time, use a function:
```
curlCmd() {
    curl "https://www.facebook.com/vivekkumar27june88"
}

curlCmd > ~/Desktop/fb.html
```

If you need to build the command piece-by-piece, use an array instead of a plain string variable:

curlCmd=(curl "https://www.facebook.com/vivekkumar27june88")
for header in "${extraHeaders[@]}"; do
    curlCmd+=(-H "$header")   # Add header options to the command
done
if [[ "$useSilentMode" = true ]]; then
    curlCmd+=(-s)
fi

"${curlCmd[@]}" > ~/Desktop/fb.html    # This is the standard idiom to expand an array

If you want to print the command, the best way to do it is usually with set -x:

set -x curl "https://www.facebook.com/vivekkumar27june88" > ~/Desktop/fb.html set +x

...but you can also do something similar with the array approach if you need to:
```
printf "%q " "${curlCmd[@]}"    # Print the array, quoting as needed
printf "\n"
"${curlCmd[@]}" > ~/Desktop/fb.html
```

51,918

Author by

Vivek Kumar

Updated on July 09, 2022

Comments

Vivek Kumar almost 2 years
I'm learning shell scripting! for the same I've tried downloading the facebook page using curl on ubuntu terminal.

t.sh content
```
vi@vi-Dell-7537(Desktop) $ cat t.sh 
curlCmd="curl \"https://www.facebook.com/vivekkumar27june88\""
echo $curlCmd
($curlCmd) > ~/Desktop/fb.html
```
Getting error when running the script as
```
vi@vi-Dell-7537(Desktop) $ ./t.sh 
curl "https://www.facebook.com/vivekkumar27june88"
curl: (1) Protocol "https not supported or disabled in libcurl
```
But if the run the command directly then it is working fine.
```
vi@vi-Dell-7537(Desktop) $ curl "https://www.facebook.com/vivekkumar27june88"
<!DOCTYPE html>
<html lang="hi" id="facebook" class="no_js">
<head><meta chars.....
```
I will appreciate if anyone let me know the mistake I am doing in the script.

I've verified that curl library have ssl enabled.
- chepner over 8 years
  
  "I'm trying to put a command in a variable, but the complex cases always fail!"
Vivek Kumar over 8 years

HI anubhava! same error even after adding -k flag to curl.
anubhava over 8 years

Check path of curl in your shell by running type curl and the check same inside the script.
Vivek Kumar over 8 years

when running $type curl getting the following output curl is hashed (/usr/bin/curl). But from script output is curl is /usr/bin/curl. Can you please tell me what hashed means here??
anubhava over 8 years

Hmm both seem to be running same curl binary. Not sure what could be the different from shell to your script. So copy/paste of curl -k "https://www.facebook.com/vivekkumar27june88" -o ~/Desktop/fb.html works fine but bash ./t.sh gives that error?
Vivek Kumar over 8 years

But I don't understand why script is making this difference. Can you please explain...Thanks :)
anubhava over 8 years

Not sure why it doesn't work for you as I have tried this curl command from shell as well from the script and it has worked fine both ways.
Vivek Kumar over 8 years

No $cmd is not working in my case on ubuntu 14.04.... vi@vi-Dell-7537(Desktop) $ ./t.sh curl -k "https://www.facebook.com/vivekkumar27june88" curl: (1) Protocol "https not supported or disabled in libcurl vi@vi-Dell-7537(Desktop) $ cat t.sh #!/bin/sh curlCmd="curl -k \"https://www.facebook.com/vivekkumar27june88\"" echo $curlCmd $curlCmd > ~/Desktop/fb.html
Gordon Davisson over 8 years

In this case, eval is needed to get the single-quotes in the command string interpreted. But eval comes with a huge collection of traps for the unwary, and you're much better off avoiding it. There are much better ways to do this, like storing the command as an array (or not storing it at all!).