Bash

manual, refs

• Mendel Cooper - Advanced Bash-Scripting Guide (aka. ABS) (한글판)
• Bash Reference Manual
• bash features
• BASH Programming - Introduction HOW-TO ★
• Bash Guide for Beginners
• Bash scripting Tutorial

==getopt

multiple arguments with one flag

깔끔한 방법이 없어보임. [1]

-o a1 -o a2 -o a3

이런식으로 계속 주는 수밖에 없는듯

long options

use getopt(not getopts) [2]

default option getopt

::

bash expansion : ranges

$ echo {d..h}
d e f g h

$ echo {d..Z}
d c b a _ ^ ]  [ Z

For more information, refer wiki.bash-hackers.org.

redirection

### cp file1 file2와 같다
$ cat < file1 > file2

string : $''

$ # Single quotation in single qoute
$ # http://stackoverflow.com/a/16605140/766330
$ echo \'sdlfkjsldf\' | sed $'s/\'//'
sdlfkjsldf'
$ #   $'string' : this is special.
$ #   below line won't work.
$ #   echo \'sdlfkjsldf\' | sed 's/\'//‘

[3]

or

$ # 'or' 
$ if [ -z "$1" ] || [ -z "$2" ]; then
>    echo "Usage: `basename $0` rslt_file target_folder"
> fi

ref. expressions used with if

extract tar archive from stdin

use - as the input file

cat largefile.tgz.aa largefile.tgz.ab | tar zxf -

[4]

find out what is using TCP port 80

# netstat -tulpn | grep :80

-p : You should be root

[5]

read from file or stdin

while read line 
do
  echo "$line"
done < "${1:-/dev/stdin}”

${1:-…} takes $1 if defined otherwise the file name of the standard input of the own process is used

[6]

no op

:

$ if true; then :; else echo; fi

[7]

Default .bashrc

/etc/skel/.bashrc

[8]

Tar the output on the fly

The same -f - option works for tarring as well.

tar -cf - something | tar -C somefolder -xvf -

GNU tar uses stdio by default:

tar -c something | tar -C somefolder -xv

[9]