使用 cat 输出运行 bash 脚本的问题（额外引号）

Question

I have a bash script in my apache directories that download some pictures and optimize them.

my script path is in : /var/www/site/storage/optimazer/photo_optimazer.sh

this script get some command from an txt file and pass it to wget

#!/usr/bin/env bash
..
THREAD="$(cat ${THREAD_FILE})";
$(command -v wget) $THREAD
...

and THREAD_FILE had this :

--user-agent="Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:90.0) Gecko/20100101 Firefox/90.0" -np -r -l 1 -A "jpg" --ignore-case -P /var/www/optimazer/public/optimazed -x http://example.com

I try to execute this bash with another one that was created at /usr/local/bin/optimaze.sh

I had to do it cuz its would be run with system services.

here is the /usr/local/bin/optimaze.sh content

#!/usr/bin/env bash

cd /var/www/site/storage/optimazer/
$(command -v bash) photo_optimazer.sh

now, when I execute the optimaze.sh its add some extra quotes to my THREAD_FILE content and broke the script and I got some errors like this :

--2021-07-30 12:56:59--  http://(windows/
Resolving (windows ((windows)... failed: Name or service not known.
wget: unable to resolve host address ‘(windows’
--2021-07-30 12:56:59--  http://nt/
Resolving nt (nt)... failed: Name or service not known.
wget: unable to resolve host address ‘nt’
--2021-07-30 12:56:59--  http://10.0;/
Resolving 10.0; (10.0;)... failed: Name or service not known.
wget: unable to resolve host address ‘10.0;’
--2021-07-30 12:56:59--  http://win64;/
Resolving win64; (win64;)... failed: Name or service not known.
wget: unable to resolve host address ‘win64;’
--2021-07-30 12:56:59--  http://x64;/
Resolving x64; (x64;)... failed: Name or service not known.
wget: unable to resolve host address ‘x64;’
--2021-07-30 12:56:59--  ftp://rv/90.0)
           => ‘/var/www/scraper/public/***/3/rv/.listing’
Resolving rv (rv)... failed: Name or service not known.
wget: unable to resolve host address ‘rv’
--2021-07-30 12:56:59--  http://gecko/20100101
Resolving gecko (gecko)... failed: Name or service not known.
wget: unable to resolve host address ‘gecko’
--2021-07-30 12:56:59--  http://firefox/90.0%22
Resolving firefox (firefox)... failed: Name or service not known.
wget: unable to resolve host address ‘firefox’

I try set -ex in photo_optimazer.sh and see what happend

 wget '--user-agent="Mozilla/5.0' '(Windows' NT '10.0;' 'Win64;' 'x64;' 'rv:90.0)' Gecko/20100101 'Firefox/90.0"' -np -A '"jpg,png"' --ignore-case --ignore-length -P /example/path -x http://example.com

It add single quotes to my THREAD output and I don't know why!

I use GNU bash, version 4.2.46(2)-release (x86_64-redhat-linux-gnu)

Answer 1

If your arguments can't contain newlines, consider changing THREAD_FILE (better named all-lowercase, as thread_file , to stay out of the reserved all-caps namespace ) to be contain one argument per line, with no shell syntax whatsoever :

--user-agent=Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:90.0) Gecko/20100101 Firefox/90.0
-np
-r
-l
1
-A
jpg
--ignore-case
-P
/var/www/optimazer/public/optimazed
-x
http://example.com

Once you've done that, you can use (in bash 4.0 or later) readarray or mapfile to read each line of that file into a new array entry:

readarray -t wget_args <"$thread_file"

...and then expand that array onto your wget command line:

wget "${wget_args[@]}"

---

_{A note, about that "reserved all-caps namespace" claim made above: The POSIX standard only strictly requires POSIX-specified tools to use only all-caps names for environment variables that modify those tools' behavior. However:}

• _{When an environment variable and a shell variable have the same name, any changes to the shell variable will also implicitly modify the environment variable .}
• _{The purpose of POSIX tools being defined to use only all-caps variables is to make variable names with at least one lower-case variable safe for application use .}

_{When all-caps variables are used for application-defined purposes, doing so discards the benefits of the restrictions POSIX places on built-in tools.}