Unix

$ cp -p seasonal/summer.csv seasonal/spring.csv backup/

$ mv seasonal/spring.csv seasonal/summer.csv backup/

$ mv xxx.csv yyy.csv

$ mv can rename directory too, same as rename a file

$ mkdir yearly$ mkdir -p yearly/2017

$ mv ~/people/agarwal.txt /tmp/scratch

~: home

/XXX: relative directory

$ cat course.txt

$ less 

$ more

$head -n 5 seasonal/winter.csv (select first 5 rows)

$ ls -R -F /home/repl
(R means "recursive", -F that prints a / after the name of every directory
and a * after the name of every runnable program.)

$ tail -n +7 seasonal/spring.csv 

(display all but the first six rows of seasonal/spring.csv) 

$man less (less manual)

$ cut -f 2-5,8 -d , values.csv 

means"select columns 2 through 5 and columns 8,
using comma as the separator".
cut uses -f (meaning "fields") to specify columns
and -d (meaning "delimiter") to specify the separator.

$ !head (rerun head command in history)

$ history

$ !3  runs the 3rd command in history

grep selects lines according to what they contain, 

$grep bicuspid seasonal/winter.csv
prints lines from winter.csv that contain "bicuspid"

• -c: print a count of matching lines rather than the lines themselves
• -h: do not print the names of files when searching multiple files
• -i: ignore case (e.g., treat "Regression" and "regression" as matches)
• -l: print the names of files that contain matches, not the matches
• -n: print line numbers for matching lines
• -v: invert the match, i.e., only show lines that don't match

grep -c incisor seasonal/autumn.csv seasonal/winter.csv

paste xxx.csv yyy.csv 最后几行开头多了一列 “，”

head -n 5 seasonal/summer.csv > top.csv

pipe:

head -n 5 seasonal/summer.csv | tail -n 3

The pipe symbol tells the shell to use the output of the command on the left
as the input to the command on the right.

wc (short for "word count") prints the number of characters, words, and lines in a file.
You can make it print only one of these using -c, -w, or -l respectively  

$ grep 2017-07 seasonal/spring.csv|wc -l 把带2017-07的行都打出来

wildcards:*

cut -d , -f 1 seasonal/*

• ? matches a single character, so 201?.txt will match 2017.txt or 2018.txt, but not 2017-01.txt.
• [...] matches any one of the characters inside the square brackets, so 201[78].txt matches 2017.txt or 2018.txt, but not 2016.txt.
• {...} matches any of the comma-separated patterns inside the curly brackets, so {*.txt, *.csv} matches any file whose name ends with .txt or .csv, but not files whose names end with .pdf.

 $ cut -d , -f 2 seasonal/winter.csv | grep -v Tooth | sort -r

flags -n and -r can be used to sort numerically and reverse the order of its output, while -b tells it to ignore leading blanks and -f tells it to fold case (i.e., be case-insensitive).

$ grep -v tooth|sort | uniq -c > ttt.csv

stop running: ctrl+C

 

$ set | grep XXX

$ echo $USER: print the value of USER

$ echo USER: print USER on the screen

$ testing=seasonal/winter.csv : create a variable

$ head -n 1 $testing: remember $ to print

$ for filetype in gif jpg png; do echo $filetype; done

$ for filename in seasonal/*.csv; do echo $filename; done

$ datasets=seasonal/*.csv  : record datasets

$ for filename in $datasets; do echo $filename; done 

$ for file in seasonal/*.csv; do grep 2017-07 $file | tail -n 1; done

move 带空格的东西：$ mv 'July 2017.csv' '2017 July data.csv' 

$ nano filename: will open filename for editing
(or create it if it doesn't already exist).

• Ctrl + K: delete a line.
• Ctrl + U: un-delete a line.
• Ctrl + O: save the file ('O' stands for 'output'). You will also need to press Enter to confirm the filename!
• Ctrl + X: exit the editor.

$ nano teeth.sh

$ bash teeth.sh > teeth.out
$ cat teeth.out 

 

$@ (dollar sign immediately followed by at-sign) to mean "all of the command-line parameters given to the script")

$ nano count-records.sh

in count-records.sh:

tail -q -n +2 $@| wc -l 

$ bash count-records.sh seasonal/*.csv > num-records.out 

process a single argument?

column.sh:
cut -d , -f $2 $1

$ bash column.sh seasonal/autumn.csv 1 

CTRL + K to cut the line, then CTRL + U twice to paste two copies of it.

# Print the first and last data records of each file.
for filename in $@
do
    head -n 2 $filename | tail -n 1
    tail -n 1 $filename
done