[UNIX CLI] Command Line(3)

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UNIX COMMAND LINE

• UNIX CLI 정리(3)
• echo를 통해 variable의 name, value을 print할 수 있음
• =를 통해 shell variable 생성 가능
• for [variable] in [list] ; do [body] ; done를 통해 for loop 실행

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echo

• variable의 value를 print할 시 $를 앞에 붙여줘야 함
• 대표적인 variable
  • OSTYPE : User’s OS type
  • HOME : User’s home directory
  • PWD : User’s present working directory
  • SHELL : Current shell program
  • USER : User’s ID

echo USER # USER

echo $USER # jisu

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=

• = 앞,뒤에 공백이 있으면 안됨
• assign된 변수를 호출할 때는 $를 사용해야 함

# assign iris.cvs as example
example=iris.csv

# print the first line of example(iris.csv)
head -n 1 $example

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=

• = 앞,뒤에 공백이 있으면 안됨
• assign된 변수를 호출할 때는 $를 사용해야 함

# assign iris.cvs as example
example=iris.csv

# print the first line of example(iris.csv)
head -n 1 $example

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for

• for [variable] in [list] ; do [body] ; done

# print all the filename in pwd
for filename in *; do echo $filename; done

# print the last row of rows including 2017-07 from all the files in directory seasonal 
for f in seasonal/*.csv; do grep 2017-07 $f | tail -n 1; done

# print all the file names and the second row in directory seasonal
for f in seasonal/*.csv; do echo $f; head -n 2 $f | tail -n 1; done

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