Unix/Linux programming

The major advantage of a hash table is its speed. Because the hash function is to take a range of key values and transform them into index values in such a way that the key values are distributed randomly across all the indices of a hash table.

We can use two major techniques to handle the collisions. They are open addressing and separate chaining. In open addressing, data items that hash to a full array cell are placed in another cell in the array. In separate chaining, each array element consist of a linked list. All data items hashing to a given array index are inserted in that list.

The file server is a machine that shares its disk storage and files with other machines on the network.

NFS stands for Network File System. NFS enables filesystems physically residing on one computer system to be used by other computers in the network, appearing to users on the remote host as just another local disk.

CVS is Concurrent Version System. It is the front end to the RCS revision control system which extends the notion of revision control from a collection of files in a single directory to a hierarchical collection of directories consisting of revision controlled files. These directories and files can be combined together to form a software release.

There are some useful commands that are being used very often. They are

► cvs checkout

► cvs update

► cvs add

► cvs remove

► cvs commit

► gdb a.out

► core core

► backtrace

Well shared libraries have 2 types

1) Static

2) Dynamic.

u can create library by

ar cr -o sharedobj.a file1.o file2.o

while file1 and file2 are headfiles (obj)

now put this sharedobj.a into /usr/lib directory

There are two ways in which a library is shared. Static and dynamic

In statically linked library the code of library is referenced at compile time and the result executable will be bigger.

I dynamically linked libraries the code of library is referenced at run time and resulting executable will be smaller. But drwaback is that at run time this will need the library to reference the library related symbols.

Basically there are 4 different types of file systems in unix ,they are as follows

1.Device file

2.Directory fil.

3.FIFO

4.Regular file

ipcrm -sem id ; for semaphores

ipcrm -shm id ; for shared mem

Sets options for your terminal.

Print or change terminal characteristics.

Multi Level Feedback Queue Scheduling with each queue in round robin.

Who | echo "total users `who|wc -l`"ls | grep -c "poem" | tee filename.txtcat file1 file2 >> filetoappendto.txt??rm -rf dir1 | tee errorlog