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.
Related
I have a program that tries to open a file:
Dir.chdir(File.dirname(__FILE__))
puts "Enter file name: ";
relPath = gets;
absPath = Dir.pwd << "/" << relPath;
if File.exist?(absPath) then
puts "File exists";
file = File.open(absPath, "r");
other code...
else
puts "File does not exist";
end
It always prints "File does not exist" even when the current directory exists and the file also exists. The file and script are in the same directory.
I am running it on Mac OS X Yosemite (10.10.3) and Ruby 2.2.0p0.
I can't explain why (albeit I have strong belief that it's for some whitespace characters) but with this little contribution it works ok.
Dir.chdir(File.dirname(__FILE__))
print "Enter file name:";
relPath = gets.chomp; #intuitively used this, and it wroked fine
absPath = File.expand_path(relPath) #used builtin function expand_path instead of string concatenation
puts absPath
puts File.file?(absPath)
if File.exist?(absPath) then
puts "File exists";
puts File.ctime(absPath) #attempting a dummy operation :)
else
puts "File does not exist";
end
runnning code
$ ls -a anal*
analyzer.rb
$ ruby -v
ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-linux]
ziya#ziya:~/Desktop/code/ruby$ ruby fileexists.rb
Enter file name:analyzer.rb
/home/ziya/Desktop/code/ruby/analyzer.rb #as a result of puts absPath
true #File.file?(absPath) => true
File exists
2015-06-11 12:48:31 +0500
That code has syntax error ("if" doesnt need "then"), and you dont have to put ";" after each line.
try
Dir.chdir(File.dirname(__FILE__))
puts "Enter file name: "
relPath = gets
absPath = "#{Dir.pwd}/#{relPath.chop}"
if File.exist?(absPath)
puts "File exists"
file = File.open(absPath, "r")
else
puts "File does not exist"
end
remember that gets will add a new line character so you will need to do a chomp, and that way to concatenate string won't work on ruby.
Your code is not idiomatic Ruby. I'd write it something like this untested code:
Dir.chdir(File.dirname(__FILE__))
puts 'Enter file name: '
rel_path = gets.chomp
abs_path = File.absolute_path(rel_path)
if File.exist?(abs_path)
puts 'File exists'
File.foreach(abs_path) do |line|
# process the line
end
else
puts 'File does not exist'
end
While Ruby supports the use of ;, they're for use when we absolutely must provide multiple commands on one line. The ONLY time I can think of needing that is when using Ruby to execute single-line commands at the command-line. In normal scripts I've never needed ; between statements.
then is used with if when we're using a single line if expression, however, we have trailing if which removes the need for then. For instance, these accomplish the same thing but the second is idiomatic, shorter, less verbose and easier to read:
if true then a = 1 end
a = 1 if true
See "What is the difference between "if" statements with "then" at the end?" for more information.
Instead of relPath and absPath we use snake_case for variables, so use rel_path and abs_path. It_is_a_readability AndMaintenanceThing.
File.absolute_path(rel_path) is a good way to take the starting directory and return the absolute path given a relative directory.
File.foreach is a very fast way to read a file, faster than slurping it using something like File.read. It is also scalable whereas File.read is not.
My task:
Write a program to rename files using regular expressions. This
program will take three command line arguments: the directory in which
to rename files, a regular expression that matches files to be
renamed, and a string to replace the regular expression match. The
primary use is to change file extensions, but it should be able to
handle replacing any portion of the file name.It should run as
follows:
./fixname.rb dir 'pattern' replacement
The program I have written is:
puts "Renaming files..."
folder_path = ARGV[0]
reg_exp = ARGV[1].to_regexp
Dir.glob(folder_path + "/*").sort.each do |f|
filename = File.basename(f, File.extname(f))
myString = String.new
myString = filename
filename = myString.gsub(reg_exp, ARGV[2])
#puts myString
File.rename(f, folder_path + "/" + filename + File.extname(f))
end
puts "Renaming complete."
The rename doesn't happen when I am using regexp, otherwise it is working. I'm getting:
error "`gsub': no implicit conversion of nil into String (TypeError)"
What you think is a regex is not, it's a String containing a regex pattern.
You need to convert that to a Regexp object. How to do that is left to you.
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.