Strange bash behavior

[featherfoot]

I am trying to troubleshoot a bash script and bash doesn’t seem to be working as I would expect:
In the examples below I have 2 trivial bash scripts. One has “#!/bin/bash” starting it and the other does not.

c@localhost:~/qt/qt-everywhere-src-6.7.2$ cat cnf
#!/bin/bash
echo "In cnf"

jc@localhost:~/qt/qt-everywhere-src-6.7.2$ ./cnf
bash: ./cnf: cannot execute: required file not found
jc@localhost:~/qt/qt-everywhere-src-6.7.2$ cat jcplay
#!/bin/bash
echo "jcplay"

jc@localhost:~/qt/qt-everywhere-src-6.7.2$ ./jcplay
jcplay
jc@localhost:~/qt/qt-everywhere-src-6.7.2$ 

The common element is that these were created in the file. ~/qt/qt-everywhere-src-6.7.2 and seems to show that “#!/bin/bash” makes the file fail.

As an experiment I created another file in my home directory, jcplay1

#!/bin/bash
echo "in jcplay1"
jc@localhost:~$ ./jcplay1
in jcplay1
jc@localhost:~$ 

c@localhost:~$ cp jcplay1 /qt/qt-everywhere-src-6.7.2/
cp: cannot create regular file '/qt/qt-everywhere-src-6.7.2/': No such file or directory
jc@localhost:~$ cp jcplay1 ~/qt/qt-everywhere-src-6.7.2/
jc@localhost:~$ cd ~/qt/qt-everywhere-src-6.7.2
jc@localhost:~/qt/qt-everywhere-src-6.7.2$ chmod +x jcplay1
jc@localhost:~/qt/qt-everywhere-src-6.7.2$ ./jcplay1
in jcplay1
jc@localhost:~/qt/qt-everywhere-src-6.7.2$ 

Is there a rule here I don’t understand, or a bug?

[Sauerland]

cnf is command-not-found:

ls -al /usr/bin/cnf
lrwxrwxrwx 1 root root 17 20. Feb 2023  /usr/bin/cnf -> command-not-found

[featherfoot]

If you notice the file jcplay exhibits the same behavior.

I admit it is a poor choice of names. What it still shows is that if the first line is “#!/bin/bash” and it is created in the ~/qt/qt-everywhere-src-6.7.2 directory, it fails.

It seems as if perhaps bash does not work correctly with Windows formatted files. Is that so?

[kasi042]

Do you actually have /bin/bash installed? What do you get from ls /bin/ | grep bash ?

[PCU]

@Sauerland

cnf is command-not-found:

That should not matter, because the OP specified the path to the file: ./

The error message required file not found seems to indicate that the file /bin/bash cannot be found. May be there are some weird characters after #!/bin/bash.

Hmm, line endings? Let’s test that:

$ cat cnf
#!/bin/bash
echo "In cnf"

$ chmod u+x cnf

$ ./cnf
In cnf

$ hexdump -C cnf
00000000  23 21 2f 62 69 6e 2f 62  61 73 68 0a 65 63 68 6f  |#!/bin/bash.echo|
00000010  20 22 49 6e 20 63 6e 66  22 0a                    | "In cnf".|
0000001a

$ unix2dos cnf
unix2dos: converting file cnf to DOS format...

$ ll cnf
-rwxr--r-- 1 joe users 28 jun 30 22:42 cnf

$ hexdump -C cnf
00000000  23 21 2f 62 69 6e 2f 62  61 73 68 0d 0a 65 63 68  |#!/bin/bash..ech|
00000010  6f 20 22 49 6e 20 63 6e  66 22 0d 0a              |o "In cnf"..|
0000001c

$ ./cnf
bash: ./cnf: cannot execute: required file not found

Well well, who would have thought?

Note that the Unix-style line ending is just 0a (line-feed), DOS-style is 0d0a (carriage-return, line-feed).

So I guess your problem is where your file originates, Linux or Windows. Just check with hexdump -C or xxd. Or even better: with the file command:

$ file cnf
cnf: Bourne-Again shell script, ASCII text executable, with CRLF line terminators

$ dos2unix cnf
dos2unix: converting file cnf to Unix format...

$ file cnf
cnf: Bourne-Again shell script, ASCII text executable

[PCU]

And NOW I see this: Linux bash shell script error cannot execute required file not found.

[jbouter]

@featherfoot What happens when you run bash cnf instead? And if that works, does changing #!/bin/bash to #!/usr/bin/env bash maybe resolve the issue?