Shell fundamentals-2

1. Cut command

Note: only the results after the operation file are output, and the contents of the file will not be changed.

Cut-d ""-f3jue 6 file

Indicates that columns 3 and 6 are displayed with spaces as delimiters

Cut-d:-f 1BI 3-5 file

Indicates that columns 1 and 3 to 5 are displayed with: as the delimiter

Cut-c n file / / take the nth character

2. Sort command

Usually used in conjunction with the uniq command

Sorting principle: compare the ASCII values of characters or control characters on each line from left to right

1) Summary

The ASCII value of a special symbol is generally less than the ASCII value of a number, and that of a number is less than that of a letter.

2) option

-n is sorted by numeric size; special symbols or letters are treated as the number 0

-r in reverse order in normal order

-t delimiter

3. Uniq command

The condition is: after sorting first, it will be effective to remove the weight.

-c count the number of repetitions

Uniq is equivalent to sort-u

4. Wc command

Option

-l line, count the number of rows

-m statistics of characters

-w word, counting the number of words, how to distinguish separated words? Separated by spaces by default

2mcl.2m is a word.

2mcl is three words.

5. Tee command

1) the tee command redirects the output to the specified file and outputs it to the screen at the same time

2) option

-an append, output append

6. Tr command

For character commands, character replacement commands

7. Split command

For file operations, large files are cut into small files

Option

-b cut the file according to the specified size, and the default file size is bytes

-l cut the file by the specified number of lines