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lseek is used to move offset of where current fd(file dscirptor) is pointing to in system-wide-file-table. #include #include #include #include extern int errno; int main(){ int rv = lseek(0, 54, SEEK_SET); if (rv == -1){ printf("Cannot seek\n"); exit(errno); } else printf("seek OK\n"); return 0; } we are trying handle fd0 which is stdin a keyboard. we cannot lseek the keyboard so it will throw o..

File System Architecture , Links, Special File Permission , Access Control Lists (Lec 20,21,23,24) (tistory.com) File System Architecture , Links, Special File Permission , Access Control Lists (Lec 20,21,23,24) in this file system there are 498784 inodes and so on.' tune2fs == allows the system adminstrator to adjust various tunable filesystem parameters on linux ext2, ext3, ext4 filesystems. i..

notice it is just displaying only the first file. let's fix this issue. we add while loop and used "argv[i]" instead of "argv[1]" . this way we can iteratively stdout files. now it works fine. #include #include #definePAGELEN20 #defineLINELEN512 void do_more(FILE *); int get_input(); int main(int argc , char *argv[]) { int i=0; if (argc == 1){ printf("This is the help page\n"); exit (0); } FILE ..

Heap Allocators Explicit allocator = require the application to explicitly free any allocated blocks. For example , the C standard library "malloc" package Implicit allocators = require the allocator to detect when an allocated block is no longer being used by the program and then free the block. for exmaple , garbage collectors. 1. brk and &end points to same address 2. char* str gets allocated..

&etext = points to first address of code section. &edata = points to initialized data section. &end = points to bss section brk = points to top of heap all the time. , when program is started &end , brk points to same address page size is 4kb address of main is below to &etext address. Initialized var is below &edata. uninitalized var is bleow &end. ii is address of heap which is above &end. res..

Normal termination The main function's return statement Any function calling exit() library call Any function calling _exit() system call Abnormal termination Calling abort() function Terminated by a signal Process reosurce limits ulimit = set the resource limits of th eshell (terminal). Process Logical Address Space

working directory is folder where it has .git file. statging works as cache between working directory and repository setting git configuration with global you can also use --local which is default. store all the needed tracking information. Head Pointer in git is now pointing to latest commit. - is changed to + , if they are colored. by "git checkout -- prog1.c" we can bring our repository prog1..

Open source packages magic spell to install open source packages ./configure make sudo make install command "configure" checks for all the needed dependency. command "make" build package with makefile and outputs .o file. after command "sudo make install" you can use hello package. GNU autotools m4 = macros , circled words are command. myexe = executable name will use automake for this project g..

myexe:hello.o gcc hello.o -o myexe hello.o:hello.c gcc -c hello.c this makefile. by executing command "gcc hello.o -o myexe" hello.o will be myexe. and same for second line. by looking at modify time make command can tell whether it need to compile it or not if hello.c 's modify time is yonger than hello.o make command will compile. notice it only compile that is not up to date. you can execute ..

every .o file start with 0 memory address. relocate symbols from thier relative locations in the .o files to their final absolute memory location in the executables. Global symbol = that are defined in one module and can be reference by other module. External symbol = Gobal symbol that are referenced by a module but are defined in some other module. declared with 'external' keyword Local symbol ..