I have two files and would like to merge them – by appending to the last line. file1.txt content file2.txt content Desired outcome – file3.txt How do I go about this, please? Note, zero is in place for null in the Stack line. Answer Using awk: When file2.txt is read, store field2 in array a using field1 as index. When
Tag: file
Delphi 10.3 Linux exclusive file access
How can I lock a file in Linux with a filestream? Creating a filestream like in the example below works perfectly in Windows, the file is locked and cannot be deleted or written to in other sessions until the stream is freed. Under Linux I can delete the file or write to it in an other session without any problems.
Searching a text file backwards from the end
I’m trying to find the string containing the substring in a text file by starting at the end. The file has tens of millions of lines. (The requirement is to read from End of the File. I cannot use sed/awk/grep etc) The below program does the job but it takes a long time. How can I make it run faster?
How to avoid creating tmp-Files on Linux?
I have a program that needs to access a file. The content of this file is in a variable and I want to avoid creating a real file. Is it possible to create some kind of virtual file?? Normally I would pipe this to the command, but STDIN already “in use”. Is there any way to pass both variables to
How to split file based on first character in Linux shell
I do have a fixedwidth flatfile with the header and detail data. Both of them can be recognized by the first character: 1 for header and 2 for detail. I want to genrate 2 different files from my fixedwidth file , each file having it’s own record set, but without type record written. File Header.txt having only type 1 records.
What is the difference between closing [close(3)] and clearing [fd_clr(3)] a file descriptor?
I am having problems with an automated software testing, which is blaming use of freed resource when I use fd_clr(3) after using close(3) in a fd. Is there something wrong with doing this? Answer FD_CLR() only changes a local fd_set, which is a C data structure to store info about a list of file descriptors. close() is a system call
Search string in file via bash but only work match
Find the only string name based on the sub string name in a file. Command used: What works: File content: Output (desired output): What does not work: File content: Output: Need output SomeApi-CURRENT.war Answer It appears, you are interested in the docBase attribute of your xml elements. Specifically those where the value string contains “current” as a substring. But this
c++ close a open() file read with mmap
I am working with mmap() to fastly read big files, basing my script on this question answer (Fast textfile reading in c++). I am using the second version from sehe answer : and it works just great. But if I implement it over a loop of several files (I just change the main() function name to: and then get the
Linux how to remove files in one folder where prefixes don’t match another folder?
I want to remove extra files in one folder where the prefix file names don’t match those in the other. A simple example will show: From folderA I want to remove frame0002.jpg and frame0006.jpg because those frameXXXX prefixes don’t exist in folderB. How can I do this automatically in 1 command line statement? Assume that the frameXXXX format will be
How to reliably read data from a file which is being continuously written by another process?
So, I am in the situation where one process is continuously (after each few seconds) writing data to a file (not appending). The data is in the form of json. Now another process has to read this file at regular intervals. Now it could be that the reading process reads it while the writing process is writing to the file.