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CSCI 330 THE UNIX SYSTEM File operations CSCI 330 THE UNIX SYSTEM File operations

OPERATIONS ON REGULAR FILES CSCI 330 - The UNIX System Create Edit Display Contents OPERATIONS ON REGULAR FILES CSCI 330 - The UNIX System Create Edit Display Contents Print Others 2

CREATING NEW FILES cat vim, emacs nano, etc. See Text Editors Section CSCI 330 CREATING NEW FILES cat vim, emacs nano, etc. See Text Editors Section CSCI 330 - The UNIX System Create Regular Files Redirect Command Output See shell Section 3

CREATING A FILE WITH CAT CSCI 330 - The UNIX System Example: % cat CREATING A FILE WITH CAT CSCI 330 - The UNIX System Example: % cat > myfile This is line 1 of input Line 2 of input ^d % 4

DISPLAY CONTENTS OF TEXT FILES cat more less pg head CSCI 330 - The DISPLAY CONTENTS OF TEXT FILES cat more less pg head CSCI 330 - The UNIX System Display Text File contents tail 5

VIEWING CONTENTS OF TEXT FILES CSCI 330 - The UNIX System command “cat” can VIEWING CONTENTS OF TEXT FILES CSCI 330 - The UNIX System command “cat” can be used to display/concatenate one or more files, displaying the output all at once Example: Display the contents of file “assign 1. txt” % cat assign 1. txt 6

VIEWING CONTENTS OF TEXT FILES CSCI 330 - The UNIX System “more”, “less” or VIEWING CONTENTS OF TEXT FILES CSCI 330 - The UNIX System “more”, “less” or "pg" display the contents of one or more files one page at a time Space bar – to advance to next page b – to go back a page Enter Key – to advance to next line Example: Display the contents of file “assign 1. txt” one page at a time % less assign 1. txt 7

VIEWING CONTENTS OF TEXT FILES CSCI 330 - The UNIX System “head” displays the VIEWING CONTENTS OF TEXT FILES CSCI 330 - The UNIX System “head” displays the beginning portion of indicated file(s); the default head size is 10 lines. Example: Display first 20 lines of file “assign 1. txt” % head -20 assign 1. txt 8

VIEWING CONTENTS OF TEXT FILES CSCI 330 - The UNIX System “tail” displays the VIEWING CONTENTS OF TEXT FILES CSCI 330 - The UNIX System “tail” displays the ending portion of indicated file(s); the default tail size is 10 lines. Example: Display last 10 lines of file “assign 1. txt” % tail assign 1. txt % tail -10 assign 1. txt 9

PRINTING FILES “lpr” send a file to the default printers available: csl or frl PRINTING FILES “lpr” send a file to the default printers available: csl or frl or ucl or lpcsl lpfrl lpucl CSCI 330 - The UNIX System (default) Example: % lpr -P frl assign 1. txt 10

PRETTY-PRINTING FILES “enscript” converts text file to Post. Script, rtf or html CSCI 330 PRETTY-PRINTING FILES “enscript” converts text file to Post. Script, rtf or html CSCI 330 - The UNIX System default: Post. Script sends output to printer Example: % enscript assign 1. txt Options: -P to specify printer -w to select output language -o to specify output file 11

CHECKING PRINTING STATUS Syntax: lpq [options] Commonly used options: -P printer shows print jobs CHECKING PRINTING STATUS Syntax: lpq [options] Commonly used options: -P printer shows print jobs on specific printer -U user-id shows print jobs for specific user -l long format of listing -a shows print jobs on all printers CSCI 330 - The UNIX System Also: “lprm” to remove unwanted print job 12

OPERATIONS ON TEXT & OTHER FILES Other File Operations Extract contents Compare files Count OPERATIONS ON TEXT & OTHER FILES Other File Operations Extract contents Compare files Count words Compress contents Sort Unique lines CSCI 330 - The UNIX System Combine contents Encrypt/ decrypt 13

COMBINING CONTENTS OF FILES CSCI 330 - The UNIX System Method 1: To vertically COMBINING CONTENTS OF FILES CSCI 330 - The UNIX System Method 1: To vertically concatenate the contents of two or more files, use cat with output redirection (>) Syntax: cat file-1 file-2 file-3 > all-file “all-file” will contain the combined contents of file -1, file-2, and file-3 in top-down (vertical) fashion 14

COMBINING CONTENTS OF FILES Method 2: To horizontally concatenate contents (columns/fields) of two or COMBINING CONTENTS OF FILES Method 2: To horizontally concatenate contents (columns/fields) of two or more files, use paste CSCI 330 - The UNIX System Syntax: paste file-1 file-2 > all-file “all-file” will contain the combined contents of file -1 and file-2 in side-by-side (horizontal) fashion 15

EXTRACTING CONTENTS OF FILES To extract one or more fields from a file, use EXTRACTING CONTENTS OF FILES To extract one or more fields from a file, use cut fields are delimited by special character CSCI 330 - The UNIX System default: TAB, change via –d option common: “: ” must specify list of fields to be extracted option -f Example: % cut -d: -f 5 /etc/passwd 16

COMPARING FILES: COMM The command named “comm” can be used to compare lines that COMPARING FILES: COMM The command named “comm” can be used to compare lines that are common in two sorted files CSCI 330 - The UNIX System Syntax: comm [options] file-1 file-2 The output contains three columns: Column 1 contains lines unique to file-1 Column 2 contains lines unique to file-2 Column 3 contains lines common to both files 17

COMPARING FILES: DIFF The command diff compares two files line by line CSCI 330 COMPARING FILES: DIFF The command diff compares two files line by line CSCI 330 - The UNIX System Syntax: diff [options] file-1 file-2 If file-1 and file-2 are the same, no output is produced If file-1 and file-2 are not the same, diff reports a series of commands that can be used to convert the first file to the second file (via the “patch” command) 18

DETERMINING FILE SIZE Recall: The “ls” command with the option “-l” gives the file DETERMINING FILE SIZE Recall: The “ls” command with the option “-l” gives the file size in bytes Use “wc” to display the size of files as number of lines, words, and characters CSCI 330 - The UNIX System Syntax: wc file-list Commonly used options: -l display the number of lines -w display the number of words -c display the number of characters 19

FILE COMPRESSION utilities to compress and uncompress files common on Linux: CSCI 330 - FILE COMPRESSION utilities to compress and uncompress files common on Linux: CSCI 330 - The UNIX System gzip, gunzip file extension: . gz Example: % gzip assign 1. txt % gunzip assign 1. txt. gz Gzip and gunzip delete their inputs So make a copy if you want one 20

COMPRESS FILE CONTENTS Bzip 2 Old CSCI 330 - The UNIX System New, better COMPRESS FILE CONTENTS Bzip 2 Old CSCI 330 - The UNIX System New, better compression compress/uncompress (. Z) Windows-compatible zip/unzip (. zip) Do not delete their input! 21

SORTING FILES To sort a text file in ascending or descending order, use sort SORTING FILES To sort a text file in ascending or descending order, use sort CSCI 330 - The UNIX System Syntax: sort [options] file-name Commonly used options: -r -n -t -k -f sort in reverse order numeric sort field delimiter field 1[, field 2] ignore case 22

REMOVING REPEATED LINES CSCI 330 - The UNIX System “uniq” removes repeated lines from REMOVING REPEATED LINES CSCI 330 - The UNIX System “uniq” removes repeated lines from a sorted input file, sending unique (unrepeated) lines to standard output Syntax: uniq sorted-file-name Commonly used options: -c place a count of repeated lines at beginning of each output line -d display the repeated lines -u display the lines that are not repeated 23

USER’S DISK QUOTA quota is upper limit of amount disk space number of files USER’S DISK QUOTA quota is upper limit of amount disk space number of files CSCI 330 - The UNIX System for each user account The command: quota -v displays the user’s disk usage and limits 2 kinds of limits: Soft limit: ex. 10 MB May be exceeded for one week System will remind you when you log on Hard limit: ex. 12 MB Cannot be exceeded 24