In a shell, we use symbol "<" to redirect standard input, and ">" to redirect standard output, and "2>" to redirect standard error. The following example sends the output from program ls to file foo : % ls -l > foo Type the above command, and then check the content of file foo with command cat foo . Our next example shows that the command sort reads lines from file foo and sort them in alphabetical order and displays the results in the standard output (terminal screen): % sort < foo 5. Archive and Extract Files with tar We often need to archive files and extract files from an archive. The Unix command for this task is tar . The command tar stands for Tape ARchive, since in the old days archives were stored on agnetic tapes. The command has numerous options. Check its manual page with man tar . One commonly used option is to create an archive file: tar -cvf your_tar_filename .tar directory_name to create a tar file your_tar_filename.tar from files in the directory directory_name . For example the following command: % tar -cvf ~/lab02.tar ~/lab02 The above command would create tar file lab02.tar containing all files under directory lab02 . The tar file is stored under your home directory. Another commonly used option is to extract all files from tar file (often called tar ball): % mkdir tmp % cd tmp % tar -xvf ~/lab02.tar The first command creates a new directory tmp . The second command sets your current directory to tmp . The last command extracts all files in directory tmp . Try the above examples. Try to create archives from other directories and extract the tar files (in a different directory). 6. File Compression and Decompression with gzip and gunzip To compress a file, say lab02.tar , use command % gzip lab02.tar this will create a compressed file named lab02.tar.gz . To uncompress it, just type the command % gunzip lab02.tar.gz Try the two commands on a file Note that on Linux system, compression and uncompression are added to the tar command. For example, you can archive files and then compress the archive in a single command using option z , such as % tar -zcvf ~/lab02.tar.gz ~/lab02 Theory Exercises Stallings (8th and 9th edition): Problems 2.1 and 2.4 Dashboard | myMurdoch Advice
/ C Programming Exercises Note, all exercises must be done via the terminal commands, not GUI tools. Do not use IDE to build your programs. Do not use GUI file managers to manage your directories and files. Also each exercise should be in a separate directory, which itself, is under a directory called lab02 1. Formatted Output with printf Last week, we used the printf function to send output to the standard output. This function allows you to construct complex strings consisting of strings, integers, floats, chars, etc, in a very flexible way. For example, the following code constructs the
You've reached the end of your free preview.
Want to read all 3 pages?
- One '14
- Shell, compress