I am using sparkfun micro sd card on an arduino uno for data logging for my sensors. I have no problem to save the results from sensors into one file. Now I wish to save files everytime i restart the arduino without delete the first one. How can I do that?
Thanks.
You can append data by using the fopen() in the append-mode (second parameter "a") or create a new file by checking the existence of the file with Arduinos exist() function. If the file exist, you can parse the string, extract for example a postfix number, increment the postfix, built a new incremented filename and check again whether file exists until there is no such file. Then create a new file with the filename. This allows you for example to have multiple ascending files.
Related
i have 1 folder which has 4 files, they are sales_jan, sales_feb, debt_jan, debt_feb.I created specific job for each sales and debt. The thing is, if i already run the job previously for sales_jan only and then there comes sales_feb after that, i dont wanna repeat reading the sales_jan again, i only want to read the newest file added that hasn't been processed. For reading the file, i pass the pattern of the specific file (ex. sales_*) but if i use it like that, then the stage will reprocessed the sales_jan again although it already has. I want to move the file already been read into another folder. How do i exactly do it in ibm datastage? if there's no way to do it, what's your suggestion for my problem. Any ideas would be appreciated.
The easiest solution is to use an after-job subroutine (ExecSH on Linux/UNIX, ExecDOS on Windows) to move the file to a different location.
Since you're using wildcards for the Sequential File stage, you're going to have to be a bit more clever in handling a situation where your job processes only some of the files. I would prefer to write this using a loop in a sequence, processing one file at a time, so that the move can be handled per-file.
you might make a flag for every file which already read by your job. For example add a maxdate field for each file. When the first file max date is less than the second file or new file Then read the latest file. It can be done by using simple linux command in sequence or tranformer. Just like Ray mentioned before
I have an STM32 application which uses two blocks of memory. In 0th block, I have a boot code (which runs just after power-on) and in 7th block, I have an application code (which may or may not run depending on the authorization decision given by the boot code).
Those two codes are developed hence generated by two separate projects. They are flashed on the specific blocks (boot code to 0th block and application code to 7th block) of STM32 NOR memory using openocd tool by giving an offset value to the openocd's write_image command.
What I would like to do basically in the boot code is that I want to calculate the hash of the application code and compare it with the reference digest. If they are equal, I will give the hand to the application code. For that, after I generate the executable (can be in elf, hex or bin format) of the application code, I want to:
Create another file (in any format listed above) which has 128K byte size
Copy the content of the executable file to the recently created file from its beginning (0 offset)
Write the hash of the executable to the last 32 bytes of the recently created file
Fill the gap with 0xFF
Finally flash this executable file (if it is still) to the 7th block of the memory
Do you think that it is doable and feasible? If so:
Which format should I use to generate the executable?
Do I have something that I need to give specific attention to achieve this?
Lastly, do you think that it makes sense to do that or is there any other more standard way for this purpose?
Thanks a lot in advance.
You just need to add an additional step to your building sequence. After the linking extract the binary file from elf
Then write a program in your favourite programming language which will calculate something and append the result to that bin file
I am new to Talend and just trying to work my way through it.
Problem Statement
I need to process a positional file, from a list of files. Need to identify the latest file first and then process only that file. I was able to identify the most updated file. And then I was able to create another flow which processes the positional file. The problem is combining these two flows so that I am able to identify the most recent file and have just that one processed.
Tried so far
Have been trying to extract the most recent file from a list within a directory. Iterated through all the files, retained their properties in a buffer. Post completion of this sub-task, read through the buffer, sorted with descending mime, extracted the top record and was able to print it using tLogRow.
All seems to be fine except I don't know how to use the filename now for next task.
I am certain this is very rudimentary but I'll be honest, I've been scourging the internet/help from quite some time now, with no success.
Any pointers would help.
The job flow is attached for your reference.
First of all, you can simplify your job by using tFileList's capabilities. It can sort files by their modified date:
Next, use tIterateToFlow to convert each iteration to a row:
(String)globalMap.get("tFileList_1_CURRENT_FILEPATH")
and tSampleRow with a range of "1", to get the most recent file.
Then store the result in a global variable. In the next subjob, just use that global variable as your filename in tFileInputPositional.
I'm relatively new to C# and am attempting to adapt a text encryption algorithm I designed in wxMaxima into a Binary encryption program in C# using Visual Studio forms. Because I am new to reading/writing binary files, I am lacking in knowledge regarding what happens when I try to read or write to a filestream.
For example, instead of encrypting a text file as I've done in the past, say I want to encrypt an executable or any other form of binary file.
Here are a few questions I don't understand:
When I open a file stream and use binaryreader will it read in an absolute duplicate of absolutely everything in the file? I want to be able to, for example, read in an entire file, delete the original file, then create a new file with the old name and write the entire binary stream back. Will this reproduce the original file exactly or will there be some sort of corruption that must otherwise be accounted for?
Because it's an encryption program, I was hoping to add in a feature that would low-level "format" the original file before deleting it so it would be theoretically inaccessible by combing the physical data of a harddisk. If I use binarywriter to overwrite parts of the original file with gibberish will it be put on the same spot on the harddisk or will the file become fragmented and actually just redirect via the FAT to some other portion of the harddisk? Obviously there's no point in overwriting the original file with gibberish if it's not over-writing the original cluster on the harddisk.
For your first question: A BinaryReader is not what you want. The name is a bit misleading: it "Reads primitive data types as binary values in a specific encoding." You probably want a FileStream.
Regarding the second question: That will not be easy: please see the "How SDelete Works" section of SDelete for an explanation. Brief extract in case that link breaks in the future:
"Securely deleting a file that has no special attributes is relatively straight-forward: the secure delete program simply overwrites the file with the secure delete pattern. What is more tricky is securely deleting Windows NT/2K compressed, encrypted and sparse files, and securely cleansing disk free spaces.
Compressed, encrypted and sparse are managed by NTFS in 16-cluster blocks. If a program writes to an existing portion of such a file NTFS allocates new space on the disk to store the new data and after the new data has been written, deallocates the clusters previously occupied by the file."
I am trying to write a script that will allow me to download numerous (1000s) of data files from a data server (e.g, http://hydro1.sci.gsfc.nasa.gov/thredds/catalog/GLDAS_NOAH10SUBP_3H/2011/345/). Unfortunately, the names of the files in each directory are not formatted in a similar way (the time that they were created were appended to the end of the file name). I need to be able to specify the file name to subset the data (I have a special tool for these data types) and download it. I cannot find a function in matlab that will extract the file names.
I have looked at URLREAD, but it downloads everything including html code.
Thanks for your help!
You can easily parse the link.
x=urlread(url)
links=regexp(x,'<a href=''([^>]+)''>','tokens')
Reads every link, you have to filter all unwanted links.
For example this gets all grb files:
a=regexp(x,'<a href=''([^>]+.grb)''>','tokens')