Bash read and ls commands not functioning

[RyanK]

Admittedly I do not know if this is the right place to ask this question but here it goes:

I am trying to write a script that will allow me to pick from movies on a remote ssh server, very simple, though I am open to any suggestions. Unfortunately there are two distinct problems.

#!/usr/bin/bash
# Linux/UNIX box with ssh key based login enabled
ssh Username\ Omitted@XXX.XXX.XXX.XXX ls "/cygdrive/d/My\ Documents/My\ Videos/Movies"
echo "What movie would you like to play? Use quotation marks"
read moviename
ssh Username\ Omitted@XXX.XXX.XXX.XXX cat "/cygdrive/d/My\ Documents/My\ Videos/Movies/*$moviename*.avi" | /cygdrive/d/Application\ Files/MPlayer-mingw32-1.0rc2/Mplayer-1.0rc2/mplayer.exe -

Now the first line comes up as:

: No such file or directory/d/My Documents/My Videos/Movies

Which I KNOW is not true because taking this identical command and putting it in the command line works.

The next problem is, after entering a value for the read command and pressing enter I get this:

': not a valid identifier read: `moviename

Yet strangely enough if I just type read moviename, enter a value, then type echo $moviename int he command line everything goes according to plan. Obviously the last command does nto get the right movie name.

I will admit my dirty secret is I am actually using cygwin on windows, but shouldn't it be the same issue?

[bclark4444]

Im assuming you're running the sshd service from within cygwin and not some Windows version.

One of the first things (issues) i see is that you are doing both doube-quoting AND backslash escaping the directory name. You should be running one or the other, like the following:
ls "/cygdrive/d/My Documents/My Videos/Movies"
Without the backslashes by the spaces.

[RyanK]

I'm sorry but I believe you are wrong. Removing the "\"s gives the following error on the ls command:

ls: cannot access /cygdrive/d/My: No such file or directory
ls: cannot access Documents/My: No such file or directory
: No such file or directoryvies

Which seems to imply very clearly that the double escaping is necessary.
Did you read the part where I mentioned I could copy and paste the exact command from the bash file into the terminal and it works?

[RyanK]

As a matter of fact every one of the commands in that script work perfectly fine when typed directly into the terminal. What am I missing here? I made the file, saved it as remotemovie.sh then ran it from cygwin with ./remotemovie.sh Why doesn't anything work?

[bclark4444]

Very strange. In order to test your environment i created a "My Video" directory under my C: drive (i dont have a D), placed a file called test.txt in there, and ran the following tests with the following results:


$ uname -a
CYGWIN_NT-5.1 BC430 1.5.25(0.156/4/2) 2007-12-14 19:21 i686 Cygwin

bclark@BC430 ~
$ ls /cygdrive/c/My\ Videos/
test.txt

bclark@BC430 ~
$ ls "/cygdrive/c/My\ Videos/"
ls: cannot access /cygdrive/c/My\ Videos/: No such file or directory

bclark@BC430 ~
$ ls "/cygdrive/c/My Videos/"
test.txt

bclark@BC430 ~
$ ls /cygdrive/c/My Videos/
ls: cannot access /cygdrive/c/My: No such file or directory
ls: cannot access Videos/: No such file or directory



As you can see, the escaped version works, the double quoted method works, but the double quoted AND escaped method does not work.

Did you read the part where I mentioned I could copy and paste the exact command from the bash file into the terminal and it works?

I did see that, but was unable to reproduce it in the manner that you say. I could only recreating your specific error was when i removed both the double quotes AND the escapes. Perhaps you can post (copy/paste) what you typed into your cygwin window and show us the results that you are seeing. Its difficult when we can only see one or the other as opposed to both, especially when you apparently have found something that goes against the way bash handles quotes and escapes.

[bigtomrodney]

Isn't bash usually in /bin/ ?

#!/usr/bin/bash

[bclark4444]

It should be accessable from both /bin and /usr/bin. If you had the wrong directory in there then the shell wouldnt execute at all. It would give some sort of bad interpreter error and stop.

[i92guboj]

Actually, the double quoting is needed because you are passing things from one shell to another. I will try to explain.

You type this on a local shell:

ssh login@server ls -ld "my dir with spaces"

Let's analyze what happens. You are invoking ssh, and passing four arguments to it, that happens on our local shell. The four arguments are (one per line):

login@server
ls
-ld
my dir with spaces

The quotes are not passed to ssh, since they are consumed by our shell and mean "this is a single argument, and not a list of separated arguments".

But, once ssh is launched, then a new shell is spawned into the ssh session (which has nothing to do with out local shell). This new shell receives that whole list of arguments, but in that list there's nothing like quotes, so, the shell inside the ssh session receives the previous list as is:

login@server
ls
-ld
my dir with spaces

No quotes: no good. The solution, you need to scape an additional pair of quotation marks on the first shell, so they reach your second shell (you get the idea how funny would it be to net 10 of these). Your method will work:

ssh login@server ls -ld "my\ dir\ with spaces"

But you could very well scape the quotations directly:

ssh login@server ls -ld "\"my dir with spaces\""

Or even you could double quote a pair of single quotes, or whatever is the correct terminology in english:

ssh login@server ls -ld "'my dir with spaces'"

Three funny ways to achieve same thing. In all these cases, the shell inside ssh would receive this second list of parameters (slightly different, but much better for our purposes).

login@server
ls
-ld
"my dir with spaces"

I am trying to write a script that will allow me to pick from movies on a remote ssh server, very simple, though I am open to any suggestions.

Mmmm, I do this same thing, but I use sshfs to mount the remote volume locally, it saves me quite a lot of problems, I can just handle them as local files. Passwordless (key pair based) authentication would also be nice if you plan to be using this a lot (otherwise you are going to be typing passwords in front of occasional observers sometimes, I guess).

#!/usr/bin/bash
# Linux/UNIX box with ssh key based login enabled
ssh Username\ Omitted@XXX.XXX.XXX.XXX ls "/cygdrive/d/My\ Documents/My\ Videos/Movies"
echo "What movie would you like to play? Use quotation marks"
read moviename
ssh Username\ Omitted@XXX.XXX.XXX.XXX cat "/cygdrive/d/My\ Documents/My\ Videos/Movies/*$moviename*.avi" | /cygdrive/d/Application\ Files/MPlayer-mingw32-1.0rc2/Mplayer-1.0rc2/mplayer.exe -

That produces me headache, try something simpler just for testing purposes, and see if it works, for example, create a file called "my test file.ext" in your server, put a simple text string into it, and try to cat it this way to see if that works:

TESTVAR=test ssh root@server cat "'/my test dir'/*${TESTVAR}*.ext"

Tip: Always use ${} if you are not sure what is going to be around a variable name. You have no guarantees that the wildcards are going to left untouch the name of your variable. And, in that case, ${} is the only thing that will let bash discern what is part of the var name and what is not.

I don't think that cygwin has something to do with your problem, it's just one shell communicating with another shell what should be worrying you. So, try my suggestions and see what happens.

By this moment, you might already have noticed that the bclark4444 example is completely different, because he is operating within a single shell, so, the standard quotation rules apply.

Cheers.

[RyanK]

Thank you for the tips, I'll try those out and let you all know how it goes.