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Session4

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Session outlines: Text Processing Tools Text Processing Tools Exercises VIM VIM Exercises Basic System Configuration Tools

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Text Processing Tools

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Extracting Text cat

• One or more files less

• Easy to read• /text• n/N• v open an editor• Used by man command to present man pages

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Extracting Text head

• First 10 lines only• -n change number of lines

tail• Last 10 lines only• -n change number of lines• -f monitoring the file

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Extracting Text cut

• Display specific columns• -d column delimiter• -f number of field• -c cut by characters

– cut -c2-5 /usr/share/dict/words

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Extracting Text Grep

• Display lines where a pattern is matched• -i case-insensitively• -n print line numbers of matches• -v print lines not containing pattern• -AX include the X lines after each match• -Bx include the X lines before each match

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Tools for Analyzing Text wc

• Counts words, lines, bytes and characters• -l only line count• -w only word count• -c only byte count• -m character count (not displayed)

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Tools for Analyzing Text sort

• Sort text and original file is not changed• -r reverse (descending) sort• -n numeric sort• -u (unique) removes duplicate lines• -t c field separator• -k X which field• uniq & uniq -c

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Tools for Analyzing Text diff and patch

• diff foo.conf-broken foo.conf-works• -u better for patchfiles• Patching

– diff -u foo.conf-broken foo.conf-works > foo.patch– patch -b foo.conf-broken foo.patch

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Tools for Analyzing Text aspell

• Interactively spell-check files:– aspell check letter.txt

• Non-interactively list mis-spelled words in– Only reads data from standard input– aspell list < letter.txt

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Tools for Manipulating Text

tr and sed

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Tools for Manipulating Text Tr

• Converts characters in one set to corresponding characters in another set

• Only reads data from STDIN• tr 'a-z' 'A-Z' < lowercase.txt

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sed (stream editor) search/replace operations on a stream of text Normally does not alter source file -i to alter source file -i.bak to back-up and alter source file

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sed Examples sed 's/dog/cat/i' pets sed 's/dog/cat/g' pets sed '1,50s/dog/cat/g' pets sed '/digby/,/duncan/s/dog/cat/g' pets sed -e 's/dog/cat/' -e 's/hi/lo/' pets

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Characters for Complex Searches ^ represents beginning of line $ represents end of line Character classes as in bash:

• [abc], [^abc]• [[:upper:]], [^[:upper:]]

Used by: grep, sed, less, others

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VIM

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VIM Advantages: Speed: Do more with fewer keystrokes Simplicity: No dependence on mouse/GUI Availability: Included with most Unix-like OSes

Disadvantages Difficulty: Steeper learning curve than simpler

editors

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Three main modes: Command Mode (default): Move cursor,

cut/paste text Insert Mode: Modify text Exit Mode: Save, quit, etc

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First steps with vim vim filename(command mode) Insert mode

• I at the cursor • A append to end of line• I insert at beginning of line• o insert new a line (below)• O insert new line (above)

Exit mode• :w writes (saves) the file to disk• :wq writes and quits• :q! quits, even if changes are lost

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Command Mode Right Arrow moves right one character 5, Right Arrow moves right five characters Arrow Keys, h, j, k, l (the same as arrows) w, b Move by word ), ( Move by sentence }, { Move by paragraph xG Jump to line x gg Jump to the first line G Jump to the last line

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Command Mode As in less

• /, n, N As in sed The selected line only

• :1,5s/cat/dog/ All of the entire file

• :%s/cat/dog/gi

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Command Mode Line

• cc • dd • yy

Letter• cl • dl • yl

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Command Mode Word

• cw• dw • yw

Sentence ahead• c) • d) • y)

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Command Mode Sentence behind

• c(• d( • y(

Paragraph above • c{ • d{ • y{

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Command Mode Paragraph below

• c} • d} • y}

u undo Ctrl-r redo U undo all changes to the last modified line

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Command Mode v starts character-oriented highlighting V starts line-oriented highlighting Visual keys used with movement keys:

• w, ), }, arrows Highlighted text can be

• Deleted• Yanked• Changed• Filtered• search/replaced, etc.

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Command Mode Ctrl-w, s splits the screen horizontally Ctrl-w, v splits the screen vertically Ctrl-w, Arrow moves between windows Ctrl-w twice, Arrow moves between windows To search for help inside vim convert to the

exit mode and ask for help by running the following

• :help

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Configuring vi and vim :set

• :set number• :set all• :set number (:se nu)• :set nonumber (:se nonu)• :set ignorecase (:se ic)• :set noignorecase (:se noic)• :set showmatch (:se sm)• :set noshowmatch(:se nosm)• :set autoindent• :set noautoindent

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Configuring vi and vim :help :help something :set

• :set textwidth=3• :set textwidth=0• :set wrapmargin=10• :set wrapmargin=0

~/.vimrc vimtutor

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Basic System Configuration Tools

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Introduction Network interfaces are named sequentially:

eth0, eth1, etc Multiple addresses can be assigned to a

device with aliases Aliases are labeled eth0:1, eth0:2, etc. Aliases are treated like separate interfaces View interface configuration with :

ifconfig [ethX] Enable interface with ifup ethX Disable interface with ifdown ethX

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Graphical Network Configuration system-config-network System > Administration > Network

Network Configuration Files For Devices /etc/sysconfig/network-scripts/ifcfg-ethX Complete list of options in

/usr/share/doc/initscripts-*/sysconfig.txt

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Example Of Dynamic Configuration DEVICE=ethX HWADDR=0:02:8A:A6:30:45 BOOTPROTO=dhcp ONBOOT=yes Type=Ethernet

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Example Of Static Configuration DEVICE=ethX HWADDR=0:02:8A:A6:30:45 IPADDR=192.168.0.254 NETMASK=255.255.255.0 GATEWAY=192.168.2.254 ONBOOT=yes Type=Ethernet

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Network Configuration Files and Other Global Network Settings /etc/sysconfig/network

• NETWORKING=yes• HOSTNAME=server1.example.com• GATEWAY=192.168.2.254

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DNS configuration Server address is specified by dhcp or in

/etc/resolv.conf• nameserver 192.168.0.254• nameserver 192.168.1.254

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Setting the System's Date and Time GUI:

• system-config-date• System->Administration->Date & Time

CLI: date [MMDDhhmm[[CC]YY][.ss]]• date 01011330• Date 010113302007.05• Date 12312359• Date 123123592007• Date 01010101.01

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Scripting Taking input with positional parameters

• $1• $2• $3• $4, etc.• $*• $#

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Scripting Taking input with the read command

• read x• read -p "Enter a filename: " file

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