Faisal Akkawi

1
Basic UNIX Commands

• Faisal Akkawi
• akkawi_at_cs.iit.edu
• Department of Computer Science
• Illinois Institute of Technology
• Chicago, IL 60616

2
Topics

• Handling Files and Directories
• Text Editors
• Compiling and Linking
• Handling Processes
• Archiving and Compressing Files
• Other Useful Commands

3
Handling Files and Directories

• ls list files
• cp copy files
• mv move files
• rm remove files
• mkdir make directories
• cd change directories
• rmdir remove directories
• pwd print working directory
• chmod change permission mode
• umask set file-creation mode mask

4
ls command

• Syntax
• ls -Options name ...
• Description
• Lists contents of directory.
• Frequently Used Options
• -a List all entries, including . and ..
• -d Do not list contents of directories
• -l Long listing
• -F Mark directories with a '/', etc.
• Examples
• ls -alF

5
cp command

• Syntax
• cp -Options file1 file2 ... target
• Description
• File1 is copied to target.
• Frequently Used Options
• -f Force remove existing file
• -i Ask before removing existing file
• -r Copy directory trees
• Examples
• cp p1.c p2.c
• cp p1.c p2.c mydir

6
mv command

• Syntax
• mv -Options file1 file2 ... target
• Description
• File1 is moved to target.
• Frequently Used Options
• -f Removes existing files without prompting the
  user
• -i Asks before removing existing file
• Examples
• mv p.c mydir

7
rm command

• Syntax
• rm -f -i file . . .
• rm -r -f -i dirname . . . file . . .
• Description
• Removes files or directories.
• Frequently Used Options
• -f Removal of files without prompting the user
• -i Interactive removal
• -r Recursive removal
• Examples
• rm -f p.o
• rm -r mydir

8
mkdir command

• Syntax
• mkdir -m mode -p dirname . . .
• Description
• Creates the specified directories.
• Options
• -m Specifies the mode to be used
• -p Create missing intermediate directories
• Examples
• mkdir -m 700 letter
• mkdir abc
• mkdir -p ./abc/def/ghi

9
cd command

• Syntax
• cd directory
• Description
• Change working directory.
• If directory is not specified, the value of
  shell parameter HOME is used as the new working
  directory.
• Examples
• cd
• cd ./abc/def/ghi
• cd ..

10
rmdir command

• Syntax
• rmdir -p -s dirname . . .
• Description
• Removes directories.
• Options
• -p Remove the directory dirname and its parent
  directories which become empty.
• -s Suppress the message when p is in effect
• Examples
• rmdir letter

11
pwd command

• Syntax
• pwd
• Description
• Prints the path name of the working (current)
  directory.
• Examples
• pwd

12
chmod command

• Syntax
• chmod -R mode file ...
• chmod -R ugoa-rwxXstl file ...
• Description
• Changes the permissions mode of a file or
  directory.
• Examples
• chmod 444 file1
• chmod ugorw p.c
• chmod 700 mydir

13
umask command I

• Syntax
• umask ooo
• Description
• Sets file-creation mode mask to ooo. The three
  octal digits refer to read/write/execute
  permissions for owner, group, and others,
  respectively.
• The value of each specified digit is subtracted
  from the corresponding digit specified by the
  system for the creation of a file.
• If ooo is omitted, the current value of the mask
  is printed.

14
umask command II

• Examples
• umask 022 removes group and others write
  permission (files normally created with mode 777
  become mode 755 files created with mode 666
  become mode 644).

15
Text Editors

• pico
• - Simple, easy-to-use text editor
• vi
• - Text editor based on an underlying line
  editor ex
• emacs
• - Powerful and extensible
• - Hard to learn

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pico

• Layout is very similar to the pine mailer

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vi

• vi Modes
• Command mode Normal and initial mode. Other
  modes return to command mode upon completion.
  ESC (escape) is used to cancel a partial
  command.
• Input mode Entered by setting any of the
  following options a A i I o O c C s S R .
  Arbitrary text may then be entered. Input mode is
  normally terminated with ESC character.
• Last line mode Reading input for / ? or
  !.Terminates by typing a carriage return

18
Compiling and Linking

• cc
• - C compiler
• - Default behavior is ANSI/ISO C
• make
• - Allows programmer to maintain, update, and
• regenerate groups of computer programs.

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cc command I

• Syntax
• cc -Options ... file ...
• Description
• .c are assumed to be C source programs.
• .o are compiled object files.
• a.out is the default output program name.
• Frequently Used Options
• -c Produce an object file
• -O Invoke optimizer

20
cc command II

• -o out Name the final output file out.
• -Dname Define the name to the C macro processor
• -Idir Seek dir for include files
• Examples
• cc p1.c

21
make command

• Syntax
• make -f makefile -eiknpqrsStuwdDPBNMOg
  names
• Frequently Used Options
• -f makefile Description file is makefile
• -n Print commands, but do not execute them.
• -u Build all targets regardless of whether they
  are
• up-to-date or not.
• Examples
• make
• make f Project1.mak

22
Handling Processes

• ps Prints information about active processes
• kill Sends a signal to a process
• ipcs Reports IPC facilities status
• ipcrm Removes IPC resource id

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ps command

• Syntax
• ps -Options
• Description
• Prints information about active processes.
• Frequently Used Options
• -A Every process now running
• -e Same as -A
• -f Full listing
• -l Long listing
• Examples
• ps -ef

24
kill command

• Syntax
• kill -signal pid . . .
• kill l (the letter L in lowercase)
• Description
• Sends a signal to the specified processes.
• The value of signal may be numeric or symbolic.
• Signal 15 is the default signal.
• kill l lists the defined signals.
• Examples
• kill 389
• kill 3 401 402
• kill -HUP 99999

25
ipcs command

• Syntax
• ipcs -Options
• Description
• Prints information about active IPC facilities.
• Without options, information is printed for
  message queues, shared memory, and semaphores
  that are currently active in the system.
• Frequently Used Options
• -q Message queues
• -m Shared memory segments
• -s Semaphores
• Examples
• ipcs -q

26
ipcrm command

• Syntax
• ipcrm -Options
• Description
• Removes messages, semaphore or shared memory
  identifiers.
• Frequently Used Options
• -q msqid Removes the message queue id
• -m shmid Removes the shared memory segment id
• -s semid Removes the semaphore id
• Examples
• ipcrm -q 231

27
Archiving and Compressing

• tar Tape archiver
• compress, uncompress, zcat Compresses and
  expands data using adaptive Lempel-Ziv coding
• gzip Compresses data using Lempel-Ziv coding
• gunzip, gzcat Decompresses files created by
  gzip, zip, compress, or pack
• pack, unpack, pcat Compresses and expands files
  using Huffman codes

28
tar command - I

• Syntax
• tar key arguments name...
• Description
• Saves and restores multiple files on a single
  file.
• The key argument controls tar's actions.
• Frequently Used Functions
• c Create
• x Extract from the tape
• t List files on the tape

29
tar command - II

• Frequently Used Modifiers
• v Verbose
• f Next argument is the name of the archive
• Examples
• tar cvf my.tar ./mydir1 ./mydir2
• tar tvf my.tar
• tar xvf my.tar

30
compress command

• Syntax
• compress -f -v -c -V -d -b
  bits name ...
• Description
• Compresses and expands data
• Compressed file name is .Z
• Frequently Used Options
• -c Write output on standard output
• -d Uncompress
• -v Verbose
• Examples
• compress my.tar
• compress -d my.tar.Z

31
uncompress command

• Syntax
• uncompress -f -v -c -V name ...
  
• Description
• Uncompresses files
• Same as compress d
• Frequently Used Options
• -c Write output on standard output
• -v Verbose
• Examples
• uncompress my.tar.Z

32
zcat command

• Syntax
• zcat name . . .
• Description
• Uncompresses files
• Same as uncompress c
• Writes the uncompressed data on standard output
• Examples
• zcat my.tar.Z gt my.tar

33
gzip command

• Syntax
• gzip -acdfhlLnNrtvV19 -S suffix name .
  . .
• Description
• Compresses and expands data
• Suffix .gz
• Frequently Used Options
• -c Write output on standard output
• -d Uncompress
• -h Help
• -r Recursive
• -v Verbose

34
gunzip command

• Syntax
• gunzip -acfhlLnNrtvV -S suffix name ...
• Description
• Uncompresses files (Same as gzip d )
• Automatically detects input format
• Frequently Used Options
• -c Write output on standard output
• -h Help
• -r Recursive
• -v Verbose

35
gzcat command

• Syntax
• gzcat -fhLV name . . .
• Description
• Uncompresses files (Same as gunzip c)
• Writes the uncompressed data on standard output
• Examples
• gzcat myfile.gz gt myfile

36
pack command

• Syntax
• pack - -f name . . .
• Description
• Compresses files
• Suffix .z
• Directories cannot be compressed
• Options
• -f Force packing
• Examples
• pack myfile

37
unpack command

• Syntax
• unpack name . . .
• Description
• Expands files created by pack
• Each .z files is replaced by its expanded version
• The new file has the .z suffix stripped from its
  name
• Examples
• unpack myfile.z

38
pcat command

• Syntax
• pcat name . . .
• Description
• Uncompresses files created by pack
• Files are unpacked and written to the standard
  output
• Examples
• pcat myfile.z
• pcat myfile
• pcat myfile.z gt myfile

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Other Useful Commands

• grep search files for a pattern
• man on-line reference manuals
• wc word, line and byte or character count

40
grep command - I

• Syntax
• grep -E -F -c -l -q -insvx
  pattern_list file . . .
• Description
• Searches the input files, selecting lines
  matching one or more patterns
• Frequently Used Options
• -i Case-insensitive search
• -l Write file names only
• -n Display line number

41
grep command - II

• Examples
• grep -i unix p1.c
• grep -n UNIX .c .h
• ps ef grep mary

42
man command

• Syntax
• man -Options -M path -T macropackage -s
  section name ...
• man -M path -k keyword ...
• Description
• On-line reference manuals
• Frequently Used Sections
• 1 User commands and application programs
• 2 System calls
• 3 Library functions
• Examples
• man -s 1 mkdir
• man mkdir
• man -k pipe

43
wc command

• Syntax
• wc -c-m -lw file . . .
• Description
• Counts lines, words, and characters
• Options
• -c Count the number of bytes
• -m Count the number of characters
• -l Count the number of newline characters
• -w Count the number of words
• Examples
• wc -l .h .c