[~] echo :$PS1:

:[\w]\[\033[00m\] :

$ PS1=" \"$PWD\" "

 "/Users/samuel.kim"

"/Users/samuel.kim" PS1="$ "

$

$ PS1="명령 내려주세요 $ "

명령 내려주세요 $

명령 내려주세요 $

$ PS1="\H $ "

google-MacBook-Air-100.local $

google-MacBook-Air-100.local $

$ echo :$PS2:

:> :

$  for x in 10 20 30

> do

> echo $x

> done

10

20

30

$ for x in 10 20 30

 do

 echo $x

 done

10

20

30

$ man bash

PROMPTING

       When executing interactively, bash displays the primary prompt  PS1

       when  it  is  ready to read a command, and the secondary prompt PS2

       when it needs more input to complete a command.  Bash allows  these

       prompt strings to be customized by inserting a number of backslash-

       escaped special characters that are decoded as follows:

              \a     an ASCII bell character (07)

              \d     the date in "Weekday Month Date" format  (e.g.,  "Tue

                     May 26")

              \D{format}

                     the format is passed to strftime(3) and the result is

                     inserted into the  prompt  string;  an  empty  format

                     results  in  a  locale-specific  time representation.

                     The braces are required

              \e     an ASCII escape character (033)

              \h     the hostname up to the first `.'

              \H     the hostname

              \j     the number of jobs currently managed by the shell

              \l     the basename of the shell's terminal device name

              \n     newline

              \r     carriage return

              \s     the name of the shell, the basename of $0  (the  por-

                     tion following the final slash)

              \t     the current time in 24-hour HH:MM:SS format

              \T     the current time in 12-hour HH:MM:SS format

              \@     the current time in 12-hour am/pm format

              \A     the current time in 24-hour HH:MM format

              \u     the username of the current user

              \v     the version of bash (e.g., 2.00)

$ echo "(yes/no)?"

(yes/no)?

$ echo "(yes/no)?\c"

(yes/no)?\c

$ echo -e "(yes/no)?\c"

(yes/no)? $

$ echo -e "(yes/no)?\c" ; read answer ; echo "$answer"

(yes/no)?yes

yes

<테스트 코드>

$ for i in "once"

  do

    echo "test"

     echo "Error" 1>&2

 done > /dev/null

<결과>

Error message

$ dstat -h

Usage: dstat [-afv] [options..] [delay [count]]

Versatile tool for generating system resource statistics

Dstat options:

  -c, --cpu              enable cpu stats

     -C 0,3,total           include cpu0, cpu3 and total

  -d, --disk             enable disk stats

     -D total,hda           include hda and total

  -g, --page             enable page stats

  -i, --int              enable interrupt stats

     -I 5,eth2              include int5 and interrupt used by eth2

  -l, --load             enable load stats

  -m, --mem              enable memory stats

  -n, --net              enable network stats

     -N eth1,total          include eth1 and total

  -p, --proc             enable process stats

  -r, --io               enable io stats (I/O requests completed)

  -s, --swap             enable swap stats

     -S swap1,total         include swap1 and total

  -t, --time             enable time/date output

  -T, --epoch            enable time counter (seconds since epoch)

  -y, --sys              enable system stats

  --aio                  enable aio stats

  --fs, --filesystem     enable fs stats

  --ipc                  enable ipc stats

  --lock                 enable lock stats

  --raw                  enable raw stats

  --socket               enable socket stats

  --tcp                  enable tcp stats

  --udp                  enable udp stats

  --unix                 enable unix stats

  --vm                   enable vm stats

  --plugin-name          enable plugins by plugin name (see manual)

  --list                 list all available plugins

  -a, --all              equals -cdngy (default)

  -f, --full             automatically expand -C, -D, -I, -N and -S lists

  -v, --vmstat           equals -pmgdsc -D total

  --bw, --blackonwhite   change colors for white background terminal

  --float                force float values on screen

  --integer              force integer values on screen

  --nocolor              disable colors (implies --noupdate)

  --noheaders            disable repetitive headers

  --noupdate             disable intermediate updates

  --output file          write CSV output to file

delay is the delay in seconds between each update (default: 1)

count is the number of updates to display before exiting (default: unlimited)

$ LC_ALL=x sar  -r -f /var/log/sa/sa03

$ LC_TIME=1 sar  -r -f /var/log/sa/sa03

$ cat xx

#!/bin/sh

if [ -z "$e" ]

then

        :

else

        echo "exit"

        exit 1

fi

echo "xx!"

$ sh xx

xx!

$ echo $?

0

$ cat xx

#!/bin/sh

if [ -f "$e" ]

then

        :

else

        echo "exit"

        exit 1

fi

echo "xx!"

$ sh xx

exit

$ echo $?

1

$ cat test.sh

#!/bin/sh

echo $1 $2 $3 $4 $5 $6 $7 $8 $9 $10

$ ./test.sh 1 2 3 4 5 6 7 8 9 30

1 2 3 4 5 6 7 8 9 10

#!/bin/sh

echo $1 $2 $3 $4 $5 $6 $7 $8 $9 ${10}

$ ./test.sh 1 2 3 4 5 6 7 8 9 30

1 2 3 4 5 6 7 8 9 30

$ echo '123456' |  sed 's/.*\(.\)$/\1/'

6

$ echo '123456' |  sed 's/^\(.\).*/\1/'

1

$ echo '123456' |  sed 's/^\(.\)\(.\).*/\1\2/'

12

$ echo '123456' |  sed 's/^\(.\)\(.\).*/\2/'

12

$ echo '1231231' | sed 's/\(12\)3/\1/'

121231

$ echo '1231231' | sed 's/\(12\)3/\1/g'

12121

$ echo 'aaaaaa' | sed 's/a/A/'

Aaaaaa

$ echo 'aaaaaa' | sed 's/a/A/5'

aaaaAa

$ echo 'aaaaaa' | sed 's/a/A/g'

AAAAAA

$ echo '123123123' | sed 's/\(12\)\(3\)/\1----\2,/g'

12----3,12----3,12----3,

$ sudo service ntpd start

$ vi /var/log/message

Jan  9 23:45:28 ntpd[12521]: restrict: error in address '::' on line 10. Ignoring...

Jan  9 23:45:28 ntpd[12521]: restrict: error in address '::1' on line 16. Ignoring...

Jan  9 23:45:32 ntpd[12521]: ntpd exiting on signal 15

$ vi /etc/ntp.conf

..

#restrict -6 default kod nomodify notrap nopeer noquery

restrict default kod nomodify notrap nopeer noquery

#restrict -6 ::1

$ sudo service ntpd start

$ vi /var/log/message

$ sudo groupadd -g 87 ntp && sudo useradd -c "Network Time Protocol" -d /var/lib/ntp -u 87 \

        -g ntp -s /bin/false ntp

$ sudo service ntpd start

$ ps -ef | grep ntp

ntp       8261     1  0 23:47 ?        00:00:00 ntpd -u ntp:ntp -p /var/run/ntpd.pid -g

$ ntpq -p

     remote           refid      st t when poll reach   delay   offset  jitter

==============================================================================

...