Basic UNIX Commands

1. Basic UNIX Commands Faisal Akkawi akkawi@cs.iit.edu Department of Computer Science Illinois Institute of Technology Chicago, IL 60616 Basic UNIX Commands

2. Topics • Handling Files and Directories • Text Editors • Compiling and Linking • Handling Processes • Archiving and Compressing Files • Other Useful Commands Basic UNIX 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 Basic UNIX Commands

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 Basic UNIX Commands

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 Basic UNIX Commands

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 Basic UNIX Commands

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 Basic UNIX Commands

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 Basic UNIX Commands

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 .. Basic UNIX Commands

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 Basic UNIX Commands

11. pwd command • Syntax • pwd • Description • Prints the path name of the working (current) directory. • Examples • pwd Basic UNIX Commands

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 ugo+rw p*.c • chmod 700 mydir Basic UNIX Commands

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. Basic UNIX Commands

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). Basic UNIX Commands

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 Basic UNIX Commands

16. pico • Layout is very similar to the pine mailer Basic UNIX Commands

17. 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 Basic UNIX Commands

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. Basic UNIX Commands

19. 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 Basic UNIX Commands

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 Basic UNIX Commands

21. make command • Syntax • make [-f makefile] [-eiknpqrsStuwdDPBNMOg] [names] • Frequently Used Options • -f makefileDescription 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 Basic UNIX Commands

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 Basic UNIX Commands

23. 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 Basic UNIX Commands

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 Basic UNIX Commands

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 Basic UNIX Commands

26. ipcrm command • Syntax • ipcrm [-Options] • Description • Removes messages, semaphore or shared memory identifiers. • Frequently Used Options • -q msqidRemoves the message queue id • -m shmidRemoves the shared memory segment id • -s semidRemoves the semaphore id • Examples • ipcrm -q 231 Basic UNIX Commands

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 Basic UNIX Commands

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 Basic UNIX Commands

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 Basic UNIX Commands

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 Basic UNIX Commands

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 Basic UNIX Commands

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 > my.tar Basic UNIX Commands

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 Basic UNIX Commands

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 Basic UNIX Commands

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 > myfile Basic UNIX Commands

36. pack command • Syntax • pack [ - ] [ -f ] name . . . • Description • Compresses files • Suffix.z • Directories cannot be compressed • Options • -f Force packing • Examples • pack myfile Basic UNIX Commands

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 Basic UNIX Commands

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 > myfile Basic UNIX Commands

39. Other Useful Commands • grep : search files for a pattern • man : on-line reference manuals • wc : word, line and byte or character count Basic UNIX Commands

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 Basic UNIX Commands

41. grep command - II • Examples • grep -i unix p1.c • grep -n UNIX *.c *.h • ps –ef | grep mary Basic UNIX Commands

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 Basic UNIX Commands

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 Basic UNIX Commands