Vowpal Wabbit command not found: No such file or directory - bash

Question

When I enter this command:
./vw -d click.train.vw -f click.model.vw --loss_function logistic
on cygwin I got this error:
-bash: ./vw: No such file or directory
I actually want to implement "PREDICTING CTR WITH ONLINE MACHINE LEARNING" website link for reference :
http://mlwave.com/predicting-click-through-rates-with-online-machine-learning/
Any help would be appreciated.

Answer 1

Answer based on common mistakes.
Execution by inexact name
Filename with blanks
Suppose you write ls in the command line and obtain the following:
$ ls
anyfile command
Then, you call your command with ./command and get the following:
$ ./command
bash: ./command: No such file or directory
Here you can think ls is wrong, but the actuality is that you can't easily recognize if a filename have, for example, leading or trailing spaces:
$ ls -Q # -Q, --quote-name -> enclose entry names in double quotes
"anyfile" "command "
As you see, here my command has a trailing space:
$ ./"command " # it works
Filename with extension
A common mistake is to call the command by the name without the extension (if any).
Let's name the command: command.sh:
$ ./command # wrong
$ ./command.sh # OK
Wrong file path
If you call your command with the prefix ./, it needs to be in your current directory ($PWD). If it is not, you will get:
$ ./command # relative path -> same as "$PWD/command"
bash: ./command: No such file or directory
In that case, you can try the following:
Executing the command by its absolute path
$ /home/user/command # absolute path (example). It starts with a slash (/).
Let the shell locate the command
If you provide just the command name without slashes, bash searches in each directory of the $PATH variable, for an executable file named command.
$ command
You can do that search with the which command:
$ which command
/usr/bin/command
If the search fails, you'll get comething like:
$ which unexistent_command
which: no unexistent_command in (/usr/local/sbin:/usr/local/bin:/usr/bin)
Broken link
Now, suppose you write ls -Q in the command line and obtain the following:
$ ls -Q
"anyfile" "command"
This time, you can be 100% secure command exists but when you try to execute it:
$ ./command
bash: ./command: No such file or directory
Reason? bash complains command doesn't exist, but what doesn't exist is the file command is pointing to by a Symbolic link. e.g.:
$ ls -l
total 0
-rw-r--r-- 1 user users 0 Jan 14 02:12 anyfile
lrwxrwxrwx 1 user users 27 Jan 14 02:12 command -> /usr/bin/unexistent_command
$ ls /usr/bin/unexistent_command
ls: cannot access /usr/bin/unexistent_command: No such file or directory
Notice that the following surely throw different errors that the one you are getting...
Execution permission
To execute a file, it must have the x bit activated. With ls -l you can check the file permission.
$ ls -l command
-rw-r--r-- 1 user users 0 Jan 3 19:52 command
In this case (it doesn't have the x bit activated), you can give permission with chmod:
$ chmod +x command
$ ls -l command
-rwxr-xr-x 1 user users 0 Jan 3 19:52 command