How to change process current folder on Delphi?
Both ways work: ChDir or SetCurrentDir. They both make the same Windows API call: SetCurrentDirectory.
If you use ChDir, an exception will be raised (in $I+ mode_) if the directory doesn't exist. So you'd want to handle the exception in that case (using try and except).
If you use SetCurrentDir, it will return false if the directory doesn't exist, and true if it was successful.
Given that SetCurrentDir is newer and ChDir is quite old, legacy (from DOS days), the former is preferred and easy to use as well.
Call the SetCurrentDir function from the SysUtils unit.
Note that the current directory is not a system property, it is a property of the process. Each process has its own current directory.
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I am currenly working on an erlang project and stuck in reading the file. I want to read a text file which is in the /src folder where all the erlang and a text file are in the same structure. Then too, I am not being able to read the file despite of specifying file paths. Any help would be appreciated.
start() ->
{ok,DataList} = file:consult("Calls.txt"),
io:format("** Calls to be made **"),
io:fwrite("~w~n",[DataList]).
The data file stores contents like : {john, [jill,joe,bob]}.
Try add folder name to the path or try set full patch to the file:
1> {ok,DataList} = file:consult("src/Calls.txt").
Notes: the error {error,enoent} mean that the file does not exist or you don't have a rights to read/write current file, for this case need set 777 rights or similar.
If you need to use src/call.txt, then this simply means that your IDE (or you) has created a src folder in which the calls.txt file has been placed. At the same time, the IDE is using a path that only includes the top level folder (i.e., the root folder for the IDE project). So src/call.txt must be used in that case. This isn’t a problem with Erlang, or even the IDE. It’s just the way your project is set up.
You can do either of two things. Move the calls.txt file up one level in the IDE file manager, so that it can be referenced as calls.txt, not src/call.txt. You can also just change the path to “calls.txt” before you run it from the command line.
enoent means "Error: No Entry/Entity". It means the file couldn't be found. When I try your code, it works correctly and outputs
[{john,[jill,joe,bob]}]
I want to let perl use the DBI module in my own path(suppose, /home/users/zdd/perl5/lib/DBI), but the sysem also has a DBI module which is /usr/lib/perl5/lib/DBI.
when I write the following code in my script, perl use the system path be default, how to force it use the one under my path?
use lib './perl5/lib/DBI';
use DBI;
sub test {
....
}
/usr/lib/perl5/lib/DBI was added to the PATH environment variable in my bash profile, it was used by many scripts, so I can't disable it.
The file for the main DBI module is in ./perl5/lib. So your path is not pointing to it.
The DBI folder contains sub-modules of DBI, e.g. DBI::Foo (the :: in module names is a representation of your module directory structure).
Try using ./perl5/lib as your library instead.
Also, using a relative path will fail if the current directory is not what you think it is. If you are in doubt, have your script call cwd to see what the current directory is.
For debugging purposes, it may be helpful to use:
no lib '[main Perl module library path here]';
That way you can be sure you are only using your custom module path. Any failure to find a module will cause an error, rather than silently using the system version.
Update: For more information, see Perldoc on use lib. Perl will use the library that you have specified first. If it does not, that indicates it is not actually finding the module in the location you have given.
In addition to what dan1111 suggested, I would also recommend you print out #INC (just before your use DBI statement) and dump %INC (just after your use DBI statement) to see what your script is doing. That may help you debug the issue.
I'd like to get a file last modified time in Delphi.
Normally something like FileAge() would do the trick, only the problem is: if I overwrite *File A* with File B using CopyFile, File A's modified date is not updated with current overwrite time as it should(?)
I get that: CopyFile also copy file attributes, but I really need to get the modified date that also works when a file is overwritten.
Is there such function? My whole application relies on modification time to decide whether or not I should proceed with files!
EDIT Just to clarify: I'm only monitoring the files. It's not my application who's modifying them.
The documentation for CopyFile says:
File attributes for the existing file are copied to the new file.
Which means that you cannot use base your program on the last modified attribute of the file, or indeed any attribute of the file. Indeed there are all sorts of ways for the last modified attribute of the file to change. It can in fact go backwards in time.
Instead I suggest that you use ReadDirectoryChangesW to keep track of modifications. That will allow you to receive notifications whenever a file is modified. You can write your program in an event based manner based on the ReadDirectoryChangesW API.
If you can't use ReadDirectoryChangesW and the file attributes, then you'll have to base your decisions on the contents of the file.
What is the difference between:
include("./somepath/class.php");
and
include("somepath/class.php");
There shouldn't be any difference, directory wise, since the former assumes relative directory structure. The only potential pitfall could be if "somepath" were actually a command to be run - some users expect to type a command for a local script file and assume it should run, when you actually have to run "./somepath" to invoke it. This, of course, only pertains to commands not on your $PATH.
I don't see any difference. "." means current directory.
. refers to the current working directory.
Sometimes you want to specify explicitly that what you want is in the current working directory, and that it is not from something in your path variable for example.
For example in PHP "somepath/somefile" is appended after paths specified in include_dir (for example: /home/var/; /home/bin/ ....) directive.
The second variant is more specific it says: search in current directory!
I am trying to change the directory in the command line from a gen_server using
os:cmd("cd d:\temp").
but nothing happense, the return is just an empty list and I remain in the same directory.
any ideas?
Try using file:set_cwd(Dir) to change your current dir.
cmd() runs a sub-shell, which you're telling to change directory, then the sub-shell exits, having changed nothing about its parent process's environment.
You want to use cd() instead, if you're in the shell, or file:set_cwd() at runtime within an Erlang program.
Another option, if you want to run another program and have its working directory be different from the one Erlang is using is to pass the {cd, Dir} tuple to open_port().