Basic UNIX Commands

This file contains a few basic UNIX commands to enable you to create directories and files, move around to find specific files, and run a few simple commands.

General

passwd

change my password (on some systems it is yppasswd or something different, so ask around)

man

read the manual page, e.g.,

`man chmod`	read about the `chmod` command
`man man`	read about the `man` command

Directories and Files

General information about file names

Absolute pathname:

Fully specifies a directory, starting at the root. For example, /home/www/CS400/index.html is an absolute pathname. Absolute pathnames always start with / (which is the name of the root directory), with one exception: ~abrady/ProgLang is an absolute name because the system will expand ~abrady to /home/abrady.

Relative pathname:

the name of a file or directory relative to the current directory; e.g.,

`myfile.c`	file in current directory
`progLang/myfile.c`	file in `progLang` directory, which is a subdirectory of the current directory
`../myfile.c`	file in parent directory (`..` means directory above current directory)
`../progLang/myfile.c`	file in `progLang` directory, which is at same level in hierarchy as the current directory (it is a child of my parent directory)

Commands for files and directories

Moving Around the Directory Hierarchy
pwd: show me where I am (print working directory)
cd dirname: change to directory dirname, e.g., cd ProgLang or cd ../ProgLang or cd ~abrady/ProgLang
Creating and Removing Directories
mkdir dirname: make a subdirectory under the current directory; call it dirname
rmdir dirname: remove the directory named dirname (must be empty)
Listing Files in a Directory
ls: list the files in the directory
ls -aF: better looking listing; lists all files, indicating directories, executables and links
ls *.html *.c: only list files ending in .html or .c
Moving, Copying, and Removing Files
mv oldname newname: rename file oldname to newname
mv oldname ProgLang/newname: move file oldname to directory ProgLang, giving it name newname
cp oldfile newfile: make a copy of oldfile, calling the copy newfile
cp oldfile ProgLang/newfile: make a copy of oldfile; put in the ProgLang directory
rm filename: remove filename (does not ask you to confirm this!)
rm *: remove all the files in the directory (don't do this!)
Looking at the Contents of Files
cat filename: display filename to the screen (cat = concatenate)
cat f1 f2 >f3: concatenate f1 and f2, calling combination f3
pg filename: display filename to screen one page at a time (use return to go to next page; - to back up)
lpr filename: print a file (pr filename on some systems)
vi filename: edit filename (but learning vi is another lesson!)
emacs filename: edit filename (but learning emacs is another lesson!)
Looking for a Specific Word or Phrase in One or More Files
grep string *.c: find which .c files contain string, e.g., grep fcn3 *.c
Compiling Programs
cc, CC: C and C++ compilers
gcc, g++: GNU C and C++ compilers
lint: fussy C syntax checker
cb: C beautifier (does pretty printing)
cflow, dbx, gdb: for C debugging; different ones are available on different systems

Others that might be useful (see man for details):

chmod: change the permissions on a file or directory
head: display the top few lines of a file
tail: display the last few lines of a file

Other handy, simple commands:

banner word: make a word big
cal: show a calendar, e.g., cal 9 1752
clear: clear the screen
date: show the date and time
echo: print to screen, e.g., echo Hi! or echo $PATH
exit, logout: exit a UNIX shell, log out of UNIX
finger: display info. about users, e.g., finger abrady@max.cs.kzoo.edu or finger Spaulding
look: find words in system dictionary, e.g., look viti
mail: send or receive email (very old, unsophisticated application)
msgs: show system messages
wc: word count (also counts lines and characters) e.g., wc myfile or wc -l myfile
who: who is logged in to the system

More powerful commands that might be useful (see man for details):

grep: look for a pattern in file(s), e.g., grep pat myfile
ftp: file transfer protocol
ps: show process status of running processes
kill: kill a process, e.g., kill -9 14238
diff: show differences between two files, e.g., diff old new
sort: sort and collate lines of a file
spell: spell checker
type command: where/what is command?
whereis command: where does this UNIX command live?
find: find files by name or other characteristics