Your daily cup of CLI

Transcription

1 Your daily cup of CLI Powerful Unix tools Campus-Booster ID : **XXXXX Copyright SUPINFO. All rights reserved

2 Your daily cup of CLI Your trainer Presenter s Name Title: **Enter title or job role. Accomplishments: **What makes the presenter qualified to present this course. Education: **List degrees if important. Publications: **Writings by the presenter on the subject of the course or presentation. Contact: **Campus-Booster ID: presenter@supinfo.com

3 Your daily cup of CLI Course objectives By completing this course, you will: n Find help. Who needs internet, anyway?. n Work with files longer than your screen. How to deal with (very) long output. n Format content. Using text tools. n Get information on an unknown file. Is this really a picture? n Find files. And to batch processing.

4 Your daily cup of CLI Course topics Course s plan: n Getting help. Reading the manual. n Pagers. Dealing with long output. n Text tools. Simple tools for powerful constructs. n Finding files. And executing tasks.

5 Your daily cup of CLI Getting help Reading the manual

6 Getting help The most important command Integrated help system man [options] [section] command Option Definitions -K -k section Search in all man pages Search in headings. See man whatis. Numeric section use. See printf(1) and printf(3). See man man Example: man man

7 Getting help Integrated help Man pages and per-command help n Man n System help n Man pages n inline help n Standalone n Invoke with --help -h n Shorter Quick reference

8 Getting help Stop-and-think Do you have any questions?

9 Getting help Stop-and-think You want to get help on the ls command. Select valid solutions. ls -l ls -h ls --help man ls ls /?

10 Getting help Stop-and-think You want to get help on the ls command. Select valid solutions. ls -l ls -h ls --help man ls ls /?

11 Your daily cup of CLI Pagers Dealing with long output

12 Pagers About pagers Page by page. n Fit output to screen n Long files n Provide advanced features n Searching n Color n Forward & backward n Used by man n KISS principle

13 Pagers More The old sailor n First pager n Loads the entire file n Can t go backward n Very limited n POSIX n Useful features n Search /pattern n for next occurrence

14 Pagers Less Most common n Second generation n On demand loading n Can go backward n Can emulate more n System default (most of) n Extra features n Search backward?pattern N previous occurrence

15 Pagers Most Most common n Third generation n Color support n Multiple windows n... n Rarely installed by default n Extra features n All less features n Color highlighting

16 Pagers Stop-and-think Do you have any questions?

17 Pagers Stop-and-think Select pager having search support. more less most

18 Pagers Stop-and-think Select pager having search support. more less most

19 Your daily cup of CLI Text tools Simple tools for powerful constructs

20 Text tools Tail Getting last lines tail [options] [file] Argument -n num -f file Definitions Get num lines from the end. Keep the file open (polling). Read from file instead of stdin Example: tail -f /var/log/messages

21 Text tools Head Getting firsts lines head [options] [file] Argument -n num file Definitions Get num lines from the beginning. Read from file instead of stdin. Example: head -n 20 /var/log/messages dmesg head -n 2 head -n 20 /var/log/messages tail

22 Text tools Grep Search for strings grep [options] string [file] Argument Definitions -i -n Case insensitive Print line number -v Reverted behavior: Select non-matching lines. Example: grep -ni usb /var/log/messages dmesg grep -i usb

23 Text tools Cut Work with formatted data cut options [file] Argument Definitions -f -d Selected fields Field separator (defaults to tab) Example: cut -d : -f1 /etc/passwd cut -d : -f1,4 /etc/passwd cut -d : -f1- /etc/passwd

24 Text tools Paste Work with formatted data paste [options] [file]... Argument Definitions -d -s Output field separator (defaults to tab) Serial mode. Serialize each file before pasting. Example: paste names numbers paste -s person1 person2 person3

25 Text tools Sort Sort lines of text sort [options] [file] Argument Definitions -f -b -h Case insensitive Ignore leading blanks Understand size suffixes like 1K, 1G when sorting values Example: ls -lh awk {print $5 $9} sort -h sort eplist.txt

26 Text tools Wc Word count, and more wc [options] [file] Argument Definitions -l, --lines -w, --words -m, --chars Count lines Count words Count chars Example: wc my-long-text.txt wc --lines my-report.txt

27 Text tools Nl Pretty output: Line numbers nl [options] [file]... Argument -s STRING -v Definitions Add string after line number First line number on each page -i Number increment between each line Example: nl main.c dmesg nl nl -i 10 hello.bas

28 Text tools Tr Translate from a set to another tr set1 [set2] Argument Definitions -d -t Delete from set1 Truncate set1 to match set2 length Example: tr -d [0-9] < file.txt tr [a-z] [A-Z] < text.txt dmesg grep -i usb tr [A-Z] [a-z]

29 Text tools Who s that file? Guessing a filetype file file Argument Definitions -i -b Output a mimetype Don t prepend the filename in output Example: file project.zip project.zip: RAR archive data, v1d, os: Win32 file picture.png picture.png: ELF 32-bit LSB executable

30 Text tools Stop-and-think Do you have any questions?

31 Text tools Stop-and-think You want to remove all remove all tabulations (\t) from a text file. Which command will you use? cut grep tr

32 Text tools Stop-and-think You want to remove all remove all tabulations (\t) from a text file. Which command will you use? cut grep tr

33 Your daily cup of CLI Finding files and executing tasks.

34 Finding files Available tools Find and locate. n Find n Real time search n Many features n Slow on big searches n Locate n Use a database Need to be updated n Less feature-rich n Significantly faster

35 Finding files Find Real time search find [start-directory] [expression] Argument -name -type -exec Definitions Search for files matching name. Use -iname for caseinsensitive search. Search for files (-type f)or directories (-type d), or other file types (man find) Execute a command on each found file. See also -ok Example: find -iname *.htm* -exec rm -f {} \; find -name *.h -exec grep -nih #define BLOCK_SIZE {} +

36 Finding files Locate Database-based search [s]locate [options] needle [s]locate [options] -r regexp Argument Definitions -i -r regexp Case-insensitive search. Search using a regular expression Example: locate library.so locate conf.d/

37 Finding files Updatedb Keeping the (s)locate database up-to-date updatedb [options] Argument -f f1,f2,... -e d1,d2,... Definitions Exclude given filesystems from the database Exclude given directories dfrom the database Example: updatedb -f tmpfs,cifs,nfs updatedb -e /tmp,/var/tmp -f cifs

38 Finding files Stop-and-think Do you have any questions?

39 Finding files Stop-and-think What s better? find locate

40 Finding files Stop-and-think What s better? find locate

41 Your daily cup of CLI Course summary Finding files Using man Unknown file? Ask the wizard! Pagers Text tools: grep, cut, tail,...

42 Your daily cup of CLI For more If you want to go into these subjects more deeply, Publications Courses Linux Technologies: Edge Computing Linux in a nutshell Web sites Conferences FOSDEM RMLL Solutions Linux

43 Congratulations You have successfully completed the SUPINFO course module n 03 Your daily cup of CLI

44 Your daily cup of CLI The end n File is your friend. n man: Read That Friendly Manual