Wednesday, September 07, 2011

Select 'Text Processing' from UNIX like 'a BOSS'


1) Learn the commands, avoid re-inventing wheels
Bootstrap method:
First, read every man page and understand that each command can be fed into any other command. There are around 2000 commands on a typical UNIX box but you only need to know a few hundred of these. If you have a specific task you can usually figure out which commands to use with the "apropos" command

Read the entire man page for important commands but just skim the top description for the others (Like encryption or security programs)


Here's how to get a list of commands available on your system (logged as root):
(The script command will screen capture into a file named typescript)
Press the tab key twice to see available commands-
#script
-tab- -tab-

Display all 2612 possibilities? (y or n)
y
!                                                icc2ps                                           ppmtobmp
./                                               icclink                                          ppmtoeyuv
411toppm                                         icctrans                                         ppmtogif
7za                                              iceauth                                          ppmtoicr
:                                                icnctrl                                          ppmtoilbm
Kobil_mIDentity_switch                           icontopbm                                        ppmtojpeg
MAKEDEV                                          iconv                                            ppmtoleaf
--More--

...
#ctl-d

# exit
Script done, file is typescript

Now that you have captured all the commands available on your system, process that file to extract commands with man pages.
Get rid of dos newlines
#unix2dos typescript
Manually cleanup "--More--" if needed using emacs or vi editor.
#emacs typescript
Loop over the commands and keep only commands with a man page
# (for k in `cat typescript`; do echo -n "$k="; man $k|wc -l ; echo; done 2>/dev/null)|sort|grep '=[1-9]' >command.list
Look over the list
awk=1612
badblocks=119
baobab=28
base64=60
basename=52
bash=4910
batch=177
bc=794
bccmd=116
bdftopcf=71



2) Start "Reading The Fine Manpages"
# man man

man(1) Manual pager utils man(1)
NAME
man - an interface to the on-line reference manuals
SYNOPSIS
man [-c|-w|-tZHT device] [-adhu7V] [-m system[,...]] [-L locale] [-p string] [-M path] [-P pager] [-r prompt] [-S list] [-e extension] [[section] page ...] ...
man -l [-7] [-tZHT device] [-p string] [-P pager] [-r prompt] file ...
man -k [apropos options] regexp ...
man -f [whatis options] page ...
DESCRIPTION
man is the system’s manual pager. Each page argument given to man is normally the name of a program, utility or function. The manual page associated with each of these arguments is then found and displayed. A section, if provided, will direct man to look only in that section of the manual. The default action is to search in all of the available sections, following a pre-defined order and to show only the first page found, even if page exists in several sections.
...

Commands:

ENTER – scroll down
”b” – take you back
”/ keyword” – search the man page for a word
asumming more as page reader

Finding Commands:

# apropos CPU
top (1) - display top CPU processes
# whatis apropos
apropos (1) - search the manual page names and descriptions
NOTE: apropos is man -k (for ”keyword search”) and whatis is man -f
(for ”fullword search”)

3) Study and practice combining these key text processing tools:
I can't even tell you how important this is.
AWK, SED, TR, GREP, SORT, UNIQ, CUT,PASTE,JOIN, HEAD, TAIL, CAT, TAC

4) Learn how to manage running processes
PS, TOP, FG, BG, KILL, vmstat, iostat, netstat, lsof, fuser, strace
ctrl-d
ctrl-c
ctrl-z


5) Learn the BASH shell
UNIX pipes combine and process streams:

Integer valueName
0Standard Input (stdin)
1Standard Output (stdout)
2Standard Error (stderr)



6) Keep going
Check out history, wget, curl, xml2, xmlformat and GNU parallel.. tons more....
(You'll be glad you did)

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