Unix Commands

To display a calendar: 

cal [month] [year] displays a calendar for integer month and integer year, if specified.

Example 1: cal 12 1998 displays a calendar for December, 1998

Example 2: cal 1998 displays a calendar for 1998

Example 3: cal displays a calendar for the current year.

To display or join files:

cat file1 displays a copy of file1 on the screen.

Example 1: cat Bank.java displays Bank.java on the screen.

Example 2: cat Bank.java Account.java displays Bank.java and Account.java on the screen.

Example 3: cat Bank.java Account.java > assignment concatenates (joins) Bank.java and Account.java and redirects the output to the file assignment. i.e. a new file is created which contains both Bank.java and Account.java

cd dir changes the current directory to dir

Example 1: cd ECR/Bank changes the current directory to ECR/Bank

Example 2: cd .. changes the current directory to the parent directory.

Example 3: cd changes the current directory to the home directory no matter what the present working directory.

chmod who operation permissions file/directory adds or deletes permissions on a file or directory for various groups of users.

who :

u - owner of the file

g - group to which the owner belongs

o - all other users

a - all users

operations :

+ - add

- - delete

permissions :

r - read permission

w - write permission

x - execute permission

Example 1: chmod go-rwx ECR deletes read, write and execute permissions on the directory ECR for all persons except the owner.

Example 2: chmod u+x bin/noctrlM adds execute permission to the file bin/noctrlM for the owner.

cp file1 file2 creates a copy of file1 called file2

Example 1: cp letter form creates a copy of letter, called form.

cp file1 dir creates a copy of file1 in the directory dir, keeping the same name.

Example 2: cp letter Archive creates a copy of letter in the directory Archive with the name letter.

Example 3: cp letter .. creates a copy of letter in the parent directory.

Example 4: cp ~marian/Bank.java . creates a copy of ~marian/Bank.java in your current directory

Example 5: cp -r ~marian/Wu/ch1 . copies the directory ~marian/Wu/ch1, all of its subdirectories and their contents to the current directory.
cp dir/file1 dir/file2 creates a copy of file1 in the directory dir, with the new name file2.

Example 5: cp letter Archive/form creates a copy of letter in the directory Archive with the name form.

Example 6: cp ~marian/Bank.java ./Cash.java creates a copy of ~marian/Bank.java in your current directory with the new name Cash.java

Example 7: cp ~marian/51/LLcode/chap02/* . creates a copy of all files in ~marian/51/LLcode/chap02 in your current directory with the new name Cash.java

date displays the current date and time.

find dir -name 'file' -print prints to the screen all files with name file below directory dir

Example 1: find ~tjones -name 'Bank.java' -print finds and prints the filenames of all files named Bank.java from the home directory tjones on down.

Example 1: find . -name 'Bank*' -print finds and prints the filenames of all files beginning with the letters "Bank" from the current directory on down.

lp -dprinter file prints file on the printer .

Example 1: lp -dstudlp1 typescript prints the file typescript on the printer studlp1 located in CU310

Example 2: lp -dproglp1 typescript prints the file typescript on the printer proglp1 located in CU101

ls [options] dir displays a list of the files in dir

Example 1: ls ECR displays a list of all files (and directories) in the ECR directory.

Example 2: ls -F displays a list of all files in the current directory with directory names followed by a / and executable files followed by a *.

Example 3: ls -a -F displays a list of all files in the current directory with directory names followed by a / and executable files followed by a * including all invisible files which begin with a period (such as .profile).

Example 4: ls -l displays a long list of all files (and directories) in the current directory, giving information about access permissions, size of the file, when it was last modified.

man unix-command displays on the screen the online manual for the unix-command

Example 1: man find displays the online information about usage of the unix command find.

mkdir dir creates a new directory called dir

Example 1: mkdir LLcode creates a new directory called LLcode

Example 2: mkdir chap02 chap03 creates two new directories called chap02 and chap03

mv file1 file2 renames file1 with the new name file2.

Example 1: mv Bank Bank.java renames Bank with the new name, Bank.java

mv file1 dir moves file1 to directory dir keeping the same name.

Example 2: mv Bank.java ECR moves Bank.java from the current directory to the directory ECR.

pwd displays the present working directory.

rm file1 removes or deletes file1

Example 1: rm letter deletes the file letter.

Example 2: rm mail/letter deletes the file letter in the directory mail.

rm dir removes or deletes dir which must be empty.

Example 1: rmdir letters deletes the empty directory letters.

Example 2: rm mail/letter deletes the file letter in the directory mail.

telnet remote-computer connects to remote-computer

Example 1: telnet studsys connects to studsys.mssc.mu.edu

Example 2: telnet vms connects to vms.csd.mu.edu

Example 3: quit ends a telnet session