Don't be a GUI rookie forever - Be in command! (line)

Don’t be a rookie forever.Be in command! (line)

Giuseppe Maxia

@datacharmerThis work is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License.

$Sunday, August 21, 11

about me -Giuseppe Maxia§ a.k.a. The Data Charmer§ QA Director, Continuent, Inc§ Long time hacking with database features§ Formerly, database consultant, designer, coder.§ A passion for QA§ An even greater passion for open source§ ... and community§ Passionate blogger§ http://datacharmer.blogspot.com

Sunday, August 21, 11

What this tutorial is about§ Providing tools and tips for command line users;§ Learn a few tricks to make you achieve more and type

less.§ Making GUI enthusiasts green with envy;

This tutorial§ A quick guide at the command line usage§ A practical case for database admins§ but ...§ Useful for all

Problem§ One document contains one date in 'mm/dd/yyyy'

format§ Need to convert the date into the 'yyyy-mm-dd' format

(or dd.mm.yyyy)

GUI USER SOLUTION§ open the document with a word processor§ change the date

§ Command line USER SOLUTION§ Probably the same

Problem§ One document contains many dates in 'mm/dd/yyyy'

format§ Need to convert the dates into the 'yyyy-mm-dd'

format (or dd.mm.yyyy)

GUI USER SOLUTION§ open the document with an advanced word processor§ hope it supports regular expressions

§ Command line USER SOLUTION§ Use vi or emacs. Do a search-and-replace operation§ Or use the next page solution

Problem§ Many documents contain many dates in 'mm/dd/yyyy'

format§ Need to convert the dates in all documents into the

'yyyy-mm-dd' format (or dd.mm.yyyy)

GUI USER SOLUTION§ Realizes that it will take days to do this manually§ Scream

§ Command Line USER SOLUTION§ uses sed or perl to do the replacement in one line

the command line

An educational story1985-901991199319941995-971998-992000-20012001-20062007-20092010-

• MS-DOS

• MS-DOS• Windows 3.0

• MS-DOS• Windows 3.0• Windows 3.1

• MS-DOS• Windows 3.0• Windows 3.1• Windows NT

• MS-DOS• Windows 3.0• Windows 3.1• Windows NT• Windows 95

• MS-DOS• Windows 3.0• Windows 3.1• Windows NT• Windows 95• Windows 98

• MS-DOS• Windows 3.0• Windows 3.1• Windows NT• Windows 95• Windows 98• Windows 2000

• MS-DOS• Windows 3.0• Windows 3.1• Windows NT• Windows 95• Windows 98• Windows 2000• Windows XP

• MS-DOS• Windows 3.0• Windows 3.1• Windows NT• Windows 95• Windows 98• Windows 2000• Windows XP• Windows Vista

• MS-DOS• Windows 3.0• Windows 3.1• Windows NT• Windows 95• Windows 98• Windows 2000• Windows XP• Windows Vista• Windows 7

• Unix shell

• Linux

• Mac OSX

Why the command line• portability• efficiency• fun

the command line (for rookies)

NO PANIC

Command line panic (for rookies)

$_Sunday, August 21, 11

Command line panic (for rookies)

$_NOW WHAT?

the command line (for rookies)

BASICS

The shell• It's a command interpreter• There are many flavors

> bash > zsh> ksh

MySQL command line client• called "mysql"

> Takes SQL commands> sends them to the server> gets results

• but it can do much more ...

other tools• Shell scripts• Aliases• Perl• awk• sort• …. and a lot of Unix little helper

which could replace everything else, of course

in case it wasn't clear (yeah, for rookies)

• command line actions are

• command line actions are> commands (the name of the application to invoke)

• command line actions are> commands (the name of the application to invoke)> parameters (optional arguments for the application)

• command line actions are> commands (the name of the application to invoke)> parameters (optional arguments for the application)> and the ENTER key

The Unix philosophy (1)• One tool for every feature

> make one tool that does one thing well> for many features, make many tools> make them work together (see next slide)

The Unix philosophy (2)• To make several tool cooperate:

> pipe the output of one tool to the input of another one.> for more actions, pipe more tools

$ sort < filename | uniq | nl

Unix pipes

inputapplication <

Unix pipes

outputapplication >

inputapplication <

Unix pipes

outputapplication >

inputapplication <

outputapplication >input<

Unix pipes

outputapplication >

inputapplication <

application | application

Unix pipes

outputapplication >

inputapplication <

input output

Unix pipes = parallel processing

output

input output

input output output

input output output input

Who gets what• shell• application• database server• pager

who gets what

shell prompt $ mysql

mysql client

mysql server

any hostwho gets what

shellmysql client

mysql server

who gets what$ mysql -u username -ppassword

First the applicationthen the server

who gets what$ mysql -u username -ppassword \ -e "select VERSION()"

goes to the server

goes to the client, then the server

who gets whatmysql> helpmysql> pager lessmysql> select 1;

goes to the server

goes to the client onlygoes to the client only

the command line

readline28

readline• Common component

> shell> mysql client> many CLI applications

Main cursor movements

Ctrl A Ctrl E

Start/End of line

Meta B Meta F

Back/Forward one word

previous/next command

Ctrl L clear screen and take current line on top

Ctrl R Search history

Changing text

Meta U Uppercase word

Meta L Lowercase word

Ctrl D delete word

Ctrl K delete to end of line

Ctrl - undo

for more tips:$ man readline

Some conventions in this talk

$ commandat the shell

mysql> command at the mysql prompt

The command line friends

handytools33

your best friends at the command line• man• ls• cd• find• grep• date• echo• pwd• mv• cp 34

man {command_name}• Tells you how to use a command

man ls

ls [directory]• lists contents of current [or given] directory

ls /some/path

ls *.txt

cd [directory]• change directory to given path• takes to $HOME directory if no path is given

cd /some/path

find {directory} [conditions]• finds files in the given directory that satisfy conditions

find $HOME/docs -name "*mouse*"

grep {pattern} filename• finds pattern matching rows in filename

grep Munich *.txt

grep "Munich\|Berlin" *.txt

grep "[0-9][0-9]:[0-9][0-9]" a.txt

date [layout]• displays the current date and time, with optional layout

dateTue Aug 16 08:33:04 CEST 2011

date '+%Y-%m-%d'2011-08-16

echo "message"• displays the given message and/or variables

echo "hi"hi

GREETINGS='Hello, there!'echo $GREETINGSHello, there!

pwd• displays the current path (Print Working Directory

pwd/home/gmax/test_dir

mv old_file_name new_file_name• moves a file from one place to another• renames a file

mv ugly.txt /some/other/pathmv *.txt /storage/texts

mv ugly.txt beautiful.txt

cp file_name destination• copies a file from one place to another• creates a copy of a file

cp ugly.txt /some/other/pathcp *.txt /storage/texts

cp ugly.txt beautiful.txt

other important friends at the command line

• rm• mkdir• rmdir• cat• sed• strings• wc• head• tail• more/less• sort

rm file_name• removes a file

rm ugly.txtrm *.txt

### DANGER!!!!rm -r * rm -rf *

mkdir/rmdir directory• creates or removes a directory

mkdir mydir

rmdir mydir

cat• shows the contents of a file

cat addresses.txt

sed [option] file • performs editing on a file

sed -e 's/Ship/Airplane/' travel.txt

strings filename• extracts printable text from a file

strings /bin/ls

wc filename• counts words (and characters and lines) in a file

wc .bashrc 72 164 2842 .bashrc# (lines, words, characters)

head/tail filename• display the first or the last lines of a file

head long_file.txthead -n 5 long_file.txt

tail long_file.txttail -n 1 long_file.txt

more/less filename• display a file with scrollable pages

# old: inefficientmore filename.txt

# new: preferredless filename.txt

sort filename• displays the ordered contents of a filename

sort unordered.txt

sort unordered.txt > sorted.txt

mixing languages

This is a story about languages

you got to understand, Bernie, it's not personal.

It's just that you are obsolete

We use language to talk to computers

10 print "hello"20 goto 10We use

languages to talk to computers

I am a polyglot

An imperfect polyglot, actually

I speak Italian

with a clear Sardinian accent

I speak English

with a distinct Italian accent

I speak Perl

with a hint of a C accent

I speak French and Spanish

I speak French and Spanishbut since I use them very little, they have melted with Italian and

EnglishSunday, August 21, 11

I speak Bash #!/bin/bash

with a strong Perl accent

I speak fluent Italian

La donzelletta vien dallacampagna, in sul calar delsole, col suo fascio dell'erbae reca in mano un mazzolino di rose e viole, onde, siccome suole, ornare ella si appresta ...

However, Sardinian comes handy sometimes

Maissavidati frimisti! (*)

(*) May you never stopSunday, August 21, 11

I speak fluent English

When in the Course of human events, it becomes necessary for one people to dissolve the political bands which have connected them with another, and to assume among the powers of the earth, the separate and equal station to which the Laws of Nature and of Nature's God entitle them, a decent respect to the opinions of mankind requires that they should declare the causes which impel them to the separation.

hmm.wrong flag

But sometimes Italian is still necessary

maestro

virtuoso

al fresco

presto

spaghettibravo

dilettantefiasco

studio

stucco

barista

cappuccino

espresso

lasagnapizza

stanza

finale

lottostiletto

vendetta soprano piano

And sometimes Italian is needed

I tuoi perversidefunti!(*)

(*) Your wicked ancestors!Sunday, August 21, 11

Although Sardinian is still effective here

Ancu ti currullidisa giustizia (*)

(*) May the rule of law chase youSunday, August 21, 11

I speak Perl fluently

#!/usr/bin/perluse strict;use warnings;use File::Find;

while (my $line = <stdin>){ # …

Sometimes, I need help from C

use Inline C;print "9 + 16 = ", add(9, 16), "\n";

__END____C__int add(int x, int y) { return x + y;}

Most of my work at the command line is Bash

$ for D in $HOME/*/; do du -sh $D;> done > /tmp/occupancy

#!/bin/bash

And sometimes, a pinch of Perl can help

$ perl -pe 's{(\d\d)-(\d\d)-(\d\d\d\d)}{$3-$1-$2}g' \ < rawfile.txt > betterfile.txt

#!/bin/bash

And then on top of all this, I need to speak SQL

$ mysql -e 'SELECT COUNT(*) FROM dbname.tbl_name WHERE col_name = 1 and other_col="A" '

I wish I could say that my SQL has a Perlish accent

use strict;use DBI;?

I wish I could say that my SQL has a Perlish accent

but it wouldn't be true

I could curse in Perl

$ perl -pe 's{(\d\d)-(\d\d)-(\d\d\d\d)}{$3-$1-$2}g' \ < rawfile.txt > betterfile.txt (*)

(*) already translated

But it would not get me far.

I will need to mix languages.

This talk will show exactly that.

Mixing languages.

Mixing languages.Yes.

Mixing languages.

$ at the command line

the Bash shell

bash81

components• commands• aliases• variables• functions

commands$ echo "something"something

aliases$ alias mydate='mysql -e "select NOW()"'$ mydate+---------------------+| now() |+---------------------+| 2010-04-12 07:14:19 |+---------------------+

aliases$ alias myself='mysql' $ myself -e "select NOW()"'+---------------------+| now() |+---------------------+| 2010-04-12 07:14:19 |+---------------------+

variables$ MYBATCH='mysql -N -B'$ MYQUERY='select curdate()' $ $MYBATCH -e "$MYQUERY"2010-04-12

nesting variables# t.sh CMD="SELECT TABLE_NAME" TBL='information_schema.tables' WHC1="TABLE_SCHEMA='mysql'" WHC2="TABLE_NAME like 'u%' " Q1="$CMD FROM $TBL" Q2="WHERE $WHC1 AND $WHC2" Q="$Q1 $Q2" echo $Q echo $Q | mysql

nesting variables$ sh t.shSELECT TABLE_NAME FROM information_schema.tables WHERE TABLE_SCHEMA='mysql' AND TABLE_NAME like 'u%'TABLE_NAMEuser

the mysql command line client

mysql>

SQL commands from a file$ mysql < filename.sqlmysql> source filename.sql

• executes the commands contained in filename.sql

• commands can be queries understood by the server

• and commands for the client

SQL commands at the command line$ application | mysql$ echo "SELECT 1" | mysql$ mysql -e "SELECT 1"

• executes the commands from standard input

• commands can be queries understood by the server

• and commands for the client

batch mode$ echo "select curdate()" | mysqlcurdate()2010-04-12

table mode$ echo "select curdate()" | mysql -t+------------+| curdate() |+------------+| 2010-04-12 |+------------+

table mode$ mysql -e "select curdate()"+------------+| curdate() |+------------+| 2010-04-12 |+------------+

Forcing batch modemysql -B -e 'select curdate()'curdate()2010-04-12

Forcing batch mode - no headermysql -N -B -e 'select curdate()'2010-04-12

IMPORTANT!

Shell + mysql$ echo "The current server's date is `mysql -N -B -e 'select curdate()'`."

$ echo "The current server's date is $(mysql -N -B -e 'select curdate()')."

advanced command line techniques

loops98

(-:((((((

loops basics$ for N in 1 2 3> do> echo $N> done123

loops basics$ for N in 1 2 3 ; do echo $N ; done123

loops basics$ for N in $(seq 1 3) ;\ do echo "this is number $N" ;\ done

this is number 1this is number 2this is number 3

loops from file$ head /usr/share/dict/words AaaaaalaaliiaamAaniaardvarkaardwolf

loops from file$ for U in \$(head /usr/share/dict/words ) ; do perl -le 'print uc shift' $U ; doneAAAAAALAALIIAAMAANI

loops from mysql results$ mysql -B -N -e 'show tables from world'CityCountryCountryLanguage

loops from mysql results$ for T in $(mysql -B -N -e 'show tables from world') ;\> do echo "CREATE TABLE world2.$T LIKE world.$T;" ; done

CREATE TABLE world2.City LIKE world.City;CREATE TABLE world2.Country LIKE world.Country;CREATE TABLE world2.CountryLanguage LIKE world.CountryLanguage;

piping loops back into mysql$ for T in $(mysql -B -N -e 'show tables from world') ;\> do echo "CREATE TABLE world2.$T LIKE world.$T;" ; done \> | mysql -vv

nested

#!#!#!#!#!

loopsSunday, August 21, 11

doing something for every tablein every database$ mysql -e "show databases"+--------------------+| Database |+--------------------+| information_schema || mysql || sakila || world |+--------------------+

doing something for every tablein every database$ mysql -e "show tables from world"+-----------------+| Tables_in_world |+-----------------+| City || Country || CountryLanguage |+-----------------+

pseudocodefor each database do for each table do print the table name

actual codealias mybatch='mysql -B -N'for D in $(mybatch -e "SHOW SCHEMAS")do for T in \ $(mybatch -e "SHOW TABLES FROM $D") do echo "$D.$T" donedone

options files

Default option files/etc/my.cnf/etc/mysql/my.cnf (Debian, Ubuntu)$BASEDIR/my.cnf$HOME/.my.cnf

Custom option files$ mysql --no-defaults$ mysql --defaults-file=filename$ mysql --defaults-extra-file=filename

Option files sections[mysqld]# option for server

[client]# option for any mysql client

[mysql]# options specific to 'mysql' CLI app

Option files example

[client]user=mynamepassword=mypassword

[mysql]prompt="mysql (\h) {\u} [\d] > "

Option files: caution# protect your option files!

$ chmod 600 $HOME/.my.cnf

$ ls -l .my.cnf-rw------- 1 [...] 10:04 .my.cnf

promptmysql> prompt gm (\h) {\u} [\d] > PROMPT set to 'gm (\h) {\u} [\d] > 'gm (localhost) {root} [(none)] > use testDatabase changedgm (localhost) {root} [test] >

# \h -> host# \u -> user# \d -> database

aliases119

((((((@@

An useful alias$ alias mysql_as_root=\'mysql --defaults_file=~/.my_as_root.cnf'

mysql_as_root -e "select user()"+----------------+| user() |+----------------+| root@localhost |+----------------+

An useful alias#.my_as_root.cnf'[client]user=rootpassword=your_mysql_root_password

[mysql]prompt="### [\h] {\u} (\d) > "

Another useful aliasalias mybatch='mysql -B -N '

mybatch -e "select version()"5.1.45-log

functions123

((((((@@( )

functions• like aliases, but with parameters

sample functionfunction grant_new { mysql_as_root -e \ "GRANT $1 on $2 to $3 identified by \"$4\" "}

$ grant_new SELECT "world.*" john \ john_secret

sample function$ mysql_as_root \ -e 'show grants for john\G'*** 1. row ***Grants for john@%: GRANT USAGE ON *.* TO 'john'@'%' IDENTIFIED BY PASSWORD '*73A88CE13374128844E3ABB500F439A9C02C53A3'*** 2. row ***Grants for john@%: GRANT SELECT ON `world`.* TO 'john'@'%'

getting query

details127

which query is being executed?# wrong.sql# this script has one erroruse test ;drop table if exists t1 ;create table t1 (id int);insert into t1 values (a);

which query is being executed?$ mysql < wrong.sqlERROR 1054 (42S22) at line 4: Unknown column 'a' in 'field list'

# WHERE IS THE ERROR?

which query is being executed?$ mysql -v < wrong.sql--------------drop table if exists t1----------------------------create table t1 (id int)----------------------------insert into t1 values (a)--------------ERROR 1054 (42S22) at line 4: Unknown column 'a' in 'field list'

getting execution times$ mysql -vv -e \'select rating,count(*) from sakila.film group by rating'+--------+----------+| rating | count(*) |+--------+----------+| G | 178 || PG | 194 || PG-13 | 223 || R | 195 || NC-17 | 210 |+--------+----------+5 rows in set (0.00 sec) 131

$echo 'select rating,count(*) from sakila.film group by rating' | mysql -vv--------------select rating,count(*) from sakila.film group by rating--------------

rating count(*)G 178PG 194PG-13 223R 195NC-17 2105 rows in set

getting execution times (batch mode)

getting execution times (batch mode)$ echo 'select rating,count(*) from sakila.film group by rating' | mysql -vvv --------------select rating,count(*) from sakila.film group by rating--------------+--------+----------+| rating | count(*) |+--------+----------+| G | 178 || PG | 194 || PG-13 | 223 || R | 195 || NC-17 | 210 |+--------+----------+5 rows in set (0.00 sec) 133

getting distinct results

getting a single value$ mysql -e "show variables like 'port'"+---------------+-------+| Variable_name | Value |+---------------+-------+| port | 3306 |+---------------+-------+

# Here, we only want the port number

getting a single value$ mysql -NB -e "show variables like 'port'" port 3306

# no header, batch mode# still two values

getting a single value$ mysql -NB \ -e "show variables like 'port'" \ | awk '{print $2}'

$ mysql -NB \ -e "show variables like 'port'" \ | perl -lane 'print $F[1]'

3306 # filtering the wanted value

getting a single value: is replication working?

$ mysql \ -e "show slave status \G" \ | grep -i slave_io_running

Slave_IO_Running: Yes

# too many things. # We only want a 'yes' or 'no'

getting a single value: is replication working?

$ mysql \ -e "show slave status \G" \ | grep -i "slave_io_running" \ | perl -lane 'print $F[1]'

# yes!

What's perl -lane?

perl -lane must turn perl

Perl command line must-know facts (1)perl -e 'print "hello\n"'# executes perl code

Perl command line must-know facts (2)perl -ne 'print if /^a/'# starts a loop from standard input# and executes the perl code for each# iteration

perl -MO=Deparse -ne 'print if /^a/'LINE: while (defined($_ = <ARGV>)) { print $_ if /^a/;}

Perl command line must-know facts (3)perl -pe 's/(^a\w+)/$1/'# like -ne, but prints each line

$ perl -MO=Deparse -pe 's/(^a\w+)/$1/'LINE: while (defined($_ = <ARGV>)) { s/(^a\w+)/$1/;}continue { print $_;}

Perl command line must-know facts (4)perl -le 'print "hello"'# strips newlines from input and adds # them to output

$ perl -e 'print "hello"'hello$ $ perl -le 'print "hello"'hello$ 144

Perl command line must-know facts (5)perl -lane 'print $F[0]'# splits input into @F array

$ echo "a b c" | \ perl -lane 'print $F[1]'b $ echo "a b c" | \ perl -lane 'print $F[2]'c 145

Perl and shell contention for $

Take the $$$ and run

Perl command line must-know facts (6)

#!/bin/bash

Beware of $VARIABLES on the command line$ perl -le "$x=1; print $x" syntax error at -e line 1, near "="Execution of -e aborted due to compilation errors.

consumed by the shell, before Perl can see it

double quotes allow the shell to interpolate variables

consumed by the shell, before Perl can see it$ perl -le '$x=1; print $x'

single quotes prevent variable consumption by the shell

combining column names

combining column names$ mysql -N -e 'desc world.City'+-------------+----------+----+-----+| ID | int(11) | NO | PRI || Name | char(35) | NO | | | CountryCode | char(3) | NO | | | District | char(20) | NO | | | Population | int(11) | NO | | +-------------+----------+----+-----+

combining column names# Expected result:# SELECT CONCAT_WS('|', # ID,Name,CountryCode,District, # Population) from City

combining column names (I)echo "select concat_ws('|', $(mysql -N -e 'desc world.City' | \ perl -lane 'push @f, $F[0];' \ -e 'END{print join ",", @f}')) from world.City" select concat_ws('|', ID,Name,CountryCode,District,Population) from world.City

combining column names (II)echo "select concat_ws('|', $( mysql -NB -e 'select group_concat(column_name) from information_schema.columns where table_name="City" and table_schema="world"')) from world.City" select concat_ws('|', ID,Name,CountryCode,District,Population) from world.City

combining column names (IIa)echo "select concat_ws('|', $( mysql -NB -e 'select group_concat(column_name) from information_schema.columns where table_name="Country" and table_schema="world"')) from world.Country"select concat_ws('|', Code,Name,Continent,Region,SurfaceArea,IndepYear,Population,LifeExpectancy,GNP,GNPOld,LocalName,GovernmentForm,HeadOfState,Capital,Code2) from world.Country

piping the result back to mysqlecho "select concat_ws('|', $( mysql -NB -e 'select group_concat(column_name) from information_schema.columns where table_name="Country" and table_schema="world"')) as line from world.Country" | mysql | head -n 4lineAFG|Afghanistan|Asia|Southern and Central Asia|652090.00|1919|22720000|45.9|5976.00|Afganistan/Afqanestan|Islamic Emirate|Mohammad Omar|1|AFNLD|Netherlands|Europe|Western Europe|41526.00|1581|15864000|78.3|371362.00|360478.00|Nederland|Constitutional Monarchy|Beatrix|5|NLANT|Netherlands Antilles|North America|Caribbean|800.00|217000|74.7|1941.00|Nederlandse Antillen|Nonmetropolitan Territory of The Netherlands|Beatrix|33|AN

dumping data

dumping a tab delimited data set # the naive way$ mysql \ -e "SELECT * into outfile '/tmp/city_data' from world.City"

# it works only if:# - /tmp/city_data does not exist# - /tmp is world writable

dumping a tab delimited data set $ mysql -B -N \ -e "SELECT * from world.City" \ > /tmp/city_data

# it works always

# if you omit the "-N" it also # includes a header

dumping a CSV $ mysql -B \ -e "SELECT * from world.City" \ | perl -F"\t" -lane \ 'print join ",", map {s/"/""/g; /^[\d.]+$/ ? $_ : qq("$_")} @F ' \ > /tmp/city_data

splits the line by tabs, instead of the default whitespace

scriptit

use the mysql.sh script§ The companion code for this tutorial§ http://tinyurl.com/cli-tut-code-2010

§ It will save you much typing§ But use it at your own risk!

Usage• download the script• load it

$ source mysql.sh

mysql.sh functions• my_batch "query"• returns the result of the query. • Without header • Without box

$ my_batch "SELECT * FROM test.t1"1 aaa2 bbb3 ccc

mysql.sh functions• my_value "what"• returns a single value

• e.g.

$ my_value "version()"5.1.49

$ my_value "@@server_id"1

mysql.sh functions• my_var "what"• returns the value of a given variable

• e.g.

$ my_var port3306

$ my_var datadir/usr/local/mysql/data

mysql.sh functions• my_status "what"• returns the value of a given status item

• e.g.

$ my_status com_select2653

$ my_status connections452

mysql.sh functions• my_dump_dataset "query" [header]• returns the values of a given query separated by tabs• if a header is requested, it will be part of the result• e.g.

$ my_dump_dataset "select * from world.City" | head -n 51 Kabul AFG Kabol 17800002 Qandahar AFG Qandahar 2375003 Herat AFG Herat 1868004 Mazar-e-Sharif AFG Balkh 1278005 Amsterdam NLD Noord-Holland 731200

mysql.sh functions• my_csv "query" [separator]• returns the values of a given query separated by

commas, or by a given separator• e.g.

$ my_csv 'select * from world.City' |head -n 3"ID","Name","CountryCode","District","Population"1,"Kabul","AFG","Kabol",17800002,"Qandahar","AFG","Qandahar",237500

inside the command line client

handling

output168

pagermysql> SELECT * FROM world.City;

rec …rec …rec …

4000 + recordsunreadable

pagermysql> pager lessPAGER set to 'less'mysql> SELECT * FROM world.City;

# [ records in a manageable window ]

mysql> nopagerPAGER set to stdout

# back to normal170

More pager tricksmysql> pager vim -# like 'less', but you can also edit# the results and eventually save # them

More pager tricksmysql> pager md5sumPAGER set to 'md5sum'mysql> select * from City;5d17ffa50d6da200dee621823ade2543 -4079 rows in set (0.01 sec)

# produce a CRC for the result set# instead of displaying it.# Useful for data comparison.# (Thanks to Baron Schwartz

Comparing data sets with md5summysql> select * from City;5d17ffa50d6da200dee621823ade2543 -

mysql> select * from City order by ID;5d17ffa50d6da200dee621823ade2543 -

mysql> select * from City order by name;5ab980f5b69a6e65d3b8cd5a95ec94e0 -

mysql> select * from City order by District;2bf37cbe91b3ffeaebc8c4b6084b8784 -

Comparing data sets with md5summysql> select * from City;5d17ffa50d6da200dee621823ade2543 -

mysql> select * from City order by ID;5d17ffa50d6da200dee621823ade2543 -

mysql> select * from City order by name;5ab980f5b69a6e65d3b8cd5a95ec94e0 -

mysql> select * from City order by District;2bf37cbe91b3ffeaebc8c4b6084b8784 -

More pager tricksmysql> pager cat > /tmp/t1.txtmysql> select "one" union select "two";mysql> pager cat > /tmp/t2.txtmysql> select "one" union select "TWO";mysql> nopagermysql> \! vimdiff -o /tmp/t[12].txt

# see the difference between two # datasets

logging sessionsmysql> tee mylog.txt

# logs everything that you see on# the screen.# your commands, the results,# warnings, error messages, and so on.

mysql> notee

# back to normal176

read more§ http://datacharmer.blogspot.com

THANKS!Question

timeComments on Twitter: @datacharmer

This work is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported License.

to do§ add dead languages

§ comparing Latin and ancient Greek to COBOL and Pascal

§ add new tricks§ {x,y} expansion in bash§ \G in MySQL§

Don't be a GUI rookie forever - Be in command! (line)

Technology

MY FAMILY CAN BE TOGETHER FOREVER · Can Be Together Forever”. He may only be able to sing one line or the words “I can” at first. Families can be together forever Through Heav’nly

1:5 to whom be the glory forever and ever. Amen. forever ...to whom be the glory forever and ever. Amen. ᾧ ἡ δόξα εἰς τοὺς αἰῶνας τῶν αἰώνων, ἀμήν

Rookie Smarts

Rookie Programme

Families Can Be Together Forever-Nalani-FC

Rookie to Rockstar

Kick-Off & Rookie Session - UZH1abddc79-bbac-483e...Kick-Off & Rookie Session October 4th 2017, 18:30. This could be YOU! Today Introduction ... –include your experience, motivation,

Families Can Be Together Forever

Rookie Manager - Guide

Concepts Rookie Book

How to Be an Aspiring Author Forever

TaylorMade-adidas Golf Finalizes ’16 Rookie Class … Golf Finalizes ’16 Rookie ... tournament to be determined later this year and will play a full bag of ... The adidas Group

2019 RULEBOOK...d) Only points gained in the Rookie Cup count towards the Top Rookie Championship. e) Top Rookie program awards top 3 in season standings. f) Top Rookie will have the

Rookie A Division

Will You Be Angry Forever?

What is Rookie Rugby?cdn2.sportngin.com/attachments/document/...Rookie Rugby can be played in any open space Age and ability determines field size and duration of playing time Rookie

Bob Marley. We'll be forever loving Jah

FTC Rookie Teams

Rookie Yearbook Three

Now Should Be Forever