Need help in option parser

Ruby
1

I am using optionparser to take in arguement. However, it seems like the
option parser does not accept “&” “|” “<” “>” as the arguement when they
are entered from the command line.

For example, I use opts.on("-d option"), when I enter -d 1&2 in the
command line, it will only accept 1 in this case.

May I know what is the reason for this and how to solve this problem?

Thanks.

2

Kwong Goh wrote:

I am using optionparser to take in arguement. However, it seems like the
option parser does not accept “&” “|” “<” “>” as the arguement when they
are entered from the command line.

For example, I use opts.on(“-d option”), when I enter -d 1&2 in the
command line, it will only accept 1 in this case.

May I know what is the reason for this and how to solve this problem?

Thanks.

Depends on what O/S and shell you’re using. In most Linux shells those
characters are interpreted by the shell. In Windows both < and > are
interpreted by cmd.com. I don’t know about the others.

You can make the shell ignore those characters by surrounding them with
quotes or escaping them with an acceptable escape character such as a
backslash.

3

Try putting 1&2 in quotes “1&2”. & | < > are used by the terminal.

Becker

4

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Kwong Goh wrote:
| I am using optionparser to take in arguement. However, it seems like the
| option parser does not accept “&” “|” “<” “>” as the arguement when they
| are entered from the command line.
|
| For example, I use opts.on(“-d option”), when I enter -d 1&2 in the
| command line, it will only accept 1 in this case.
|
| May I know what is the reason for this and how to solve this problem?

Try to use a ‘dir > text.txt’, or ‘ls > text.txt’, or ‘dmesg | grep a’
on the command line.

The symbols OptionPArse doesn’t accept are reserved by the OS.

(| is the pipe in *NIX, && allows comamnd chaining in Windows and *NIX,
< and > are redirectors, which allow the use of a file as input to a
command, or direct the output of a command to a file, respectively.

There is no way I am aware of to circumvent these, except “Stop using
them”. Maybe others know more.

Phillip G.
Twitter: twitter.com/cynicalryan

Make sure all variables are initialised before use.
~ - The Elements of Programming Style (Kernighan & Plaugher)
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