This works:
system("ruby #{File.dirname(__FILE__) + '/Test')}")
but this
`ruby #{File.dirname(__FILE__) + '/Test'}`
does not run the script Test
And this:
system("ruby #{File.dirname(__FILE__) + '/Test #{arg}'")
does not take the arg value.
What am I doing wrong?
The second doesn't work because there's a unbalanced trailing double-quote (") and closing parenthesis ()) which is probably raising and error, but you're not seeing it because the back-ticks ignore STDERR:
`ruby #{File.dirname(__FILE__) + '/Test'")}`
The third one doesn't work because you're trying to interpolate a variable into a fixed string enclosed in single-quotes, which is also missing a terminating }:
system("ruby #{File.dirname(__FILE__) + '/Test #{arg}'")
You'd see this stand out if you didn't embed the string calculation in your string interpolation:
cmd_file = File.dirname(__FILE__) + '/Test #{arg}'
system("ruby #{ cmd_file }")
Fixing the quoting and using the intrinsic File.join for correctness:
cmd_file = File.join(File.dirname(__FILE__), "Test #{arg}")
system("ruby #{ cmd_file }")
Related
Lua's io.popen is useful for capturing stdout of a command, but it relies on /bin/sh for word-splitting, glob expansion, etc.
So I can do the following and it works great
-- this unfortunately uses /bin/sh
local command = "ls -1";
local ph = io.popen(command, "r")
while true do
local line = ph:read()
if line == nil then
break
end
io.write("I read a line! " .. line .. "\n")
end
io.write("Done with line reading!\n")
Is there some function that's a thin wrapper around spawn* or fork/exec* that I can pass {"ls", "-1"} to in order to avoid the shell?
I have tried the regex from the answer of this question: check directory path for symbols range and ".." up directory sign
Which was not working for me. If I passed my script a directory like this "/home/local/NKU/dixonc3/test/" it would not match the regex.
So I just tried to start out with something simple such as if a directory starts with a slash / or a tilde ~ it will pass.
^[~/].*$
even when I use this as my regex in the code below if I pass it a ~ tilde it gives me an error
./rename.rb:23:in `exists?': can't convert nil into String (TypeError)
from ./rename.rb:23:in `rename'
from ./rename.rb:33:in `<main>'
Below is my Ruby code
currDir = ""
#
# regex is from stack overflow question:
#dirRegex = Regexp.new '^(?!.*[\\/]\.{2}[\\/])(?!\.{2}[\\/])[-\w.\\/]+$'
dirRegex = Regexp.new '^[~/]*$'
if ARGV.length == 1 && ($1.to_s.match dirRegex)
currDir = $1
puts $1
puts "#{currDir}"
puts ARGV.length
else
currDir = "./"
puts $1
puts "#{currDir}"
puts ARGV.length
end
Your regex is matching on a single character (~ or / or nothing). It should be:
dirRegex = Regexp.new '^[~/].*$'
To match on an opening character of ~ or / and the rest.
I want to parse user input using named captures for readability.
When they type a command I want to capture some params and pass them. I'm using RegExps in a case statement and thus I can't assign the return of /pattern/.named_captures.
Here is what I would like to be able to do (for example):
while command != "quit"
print "Command: "
command = gets.chomp
case command
when /load (?<filename>\w+)/
load(filename)
end
end
named captures set local variables when this syntax.
regex-literal =~ string
Dosen't set in other syntax. # See rdoc(re.c)
regex-variable =~ string
string =~ regex
regex.match(string)
case string
when regex
else
end
I like named captures too, but I don't like this behavior.
Now, we have to use $~ in case syntax.
case string
when /(?<name>.)/
$~[:name]
else
end
This is ugly but works for me in Ruby 1.9.3:
while command != "quit"
print "Command: "
command = gets.chomp
case command
when /load (?<filename>\w+)/
load($~[:filename])
end
end
Alternatively you can use the English extension of $~, $LAST_MATCH_INFO.
I want to parse user input using named captures for readability.
When they type a command I want to capture some params and pass them. I'm using RegExps in a case statement and thus I can't assign the return of /pattern/.named_captures.
Here is what I would like to be able to do (for example):
while command != "quit"
print "Command: "
command = gets.chomp
case command
when /load (?<filename>\w+)/
load(filename)
end
end
named captures set local variables when this syntax.
regex-literal =~ string
Dosen't set in other syntax. # See rdoc(re.c)
regex-variable =~ string
string =~ regex
regex.match(string)
case string
when regex
else
end
I like named captures too, but I don't like this behavior.
Now, we have to use $~ in case syntax.
case string
when /(?<name>.)/
$~[:name]
else
end
This is ugly but works for me in Ruby 1.9.3:
while command != "quit"
print "Command: "
command = gets.chomp
case command
when /load (?<filename>\w+)/
load($~[:filename])
end
end
Alternatively you can use the English extension of $~, $LAST_MATCH_INFO.
I try to modify "/foo/bar/dir" to "\/foo\/bar\/dir" by ruby gsub command.
I test it in irb the result is
x = "/foo/bar/dir"
x.gsub("/","\/")
=> "/foo/bar/dir"
x.gsub("/","\\/")
=> "\\/foo\\/bar\\/dir"
Is it possible to replace "/" with "/" by gsub ?
Source of problems:
I try to execute "string in command line" and "real_path" is my variable
real_path = "/home/me/www/idata"
path = real_path.gsub("/","\\/")
=> \\/home\\/me\\/www\\/idata
# But what I expect is \/home\/me\/www\/idata
run "sed 's/SHARE_PATH/#{path}/g' #{path}/config/sphinx.yml > #{path}/config/sphinx.tmp.yml"
result from "run" command is
"sh -c 'sed '\''s/SHARE_PATH/\\/home\\/me\\/www\\/idata\\/shared/g .... "
I need is only one back slash like
"sh -c 'sed '\''s/SHARE_PATH/\/home\/me\/www\/idata\/shared/g .... "
"run" is command from Capistrano
my solution is
use single quote instead of double quote like this
path = real_path.gsub("/",'\/')
You have written:
x = "/foo/bar/dir"
x.gsub("/","\\/")
=> "\\/foo\\/bar\\/dir"
so You did what You had asked before. x.gsub("/","\\/") in fact evaluates to "\/foo\/bar\/dir" but irb prints return value of inspect method instead of to_s.
Edit: Did You mean
real_path.gsub("/","\/")
istead of
real_path.gsub("\/","\/")
Anyway the output is correct - You changed / with \/ so You have
"sh -c 'sed '\''s/SHARE_PATH/\/home\/me\/www\/idata\/shared/g'\'' .... "`
instead of
`"sh -c 'sed '\''s/SHARE_PATH//home/me/www/idata/shared/g'\'' .... "`
and result is different from irb's result (notice the lack of doubled backslash).
For path manipulation I recommend using File.join (documentation)
By the way: why are You modifying the path this way? (1)
Edit2: Why are You asking about changing "/" to "/" but write the following line?
path = real_path.gsub("\/","\\/")
What are You trying to achieve? And what is Your answer to question (1) ?
Edit3:
Here We go:
>> real_path = "/foo/bar/dir"
=> "/foo/bar/dir"
>> path = real_path.gsub("/", "\\/")
=> "\\/foo\\/bar\\/dir"
>> puts "sed 's/SHARE_PATH/#{path}/g' #{path}/config/sphinx.yml > #{path}/config/sphinx.tmp.yml"
sed 's/SHARE_PATH/\/foo\/bar\/dir/g' \/foo\/bar\/dir/config/sphinx.yml > \/foo\/bar\/dir/config/sphinx.tmp.yml
=> nil
>>
but I do not understand why You need backslash in a path?
Yes
irb(main):028:0> (t = x.gsub("/", "\\/")) && nil
=> nil
irb(main):029:0> t
=> "\\/foo\\/bar\\/dir"
irb(main):030:0> puts t
\/foo\/bar\/dir
=> nil
Your first example actually did what you wanted, but the .inspect method that irb is using is escaping backslashes, so it looked like there were extras. If you had used puts you would have seen the real result.