Linux diary: Cut grep sort WC & uniq

Linux diary: Cut grep sort WC & uniq

After several days, I finally had time to write a Linux blog. Recently I felt a lot of emotion, but I was unable to give up my love for Linux. So I continued my research and didn't want to delay my step forward due to chores, I am literature and art.

Cut command.

The basic usage of cut is as follows:

Cut-D 'separator '-F Fields

Cut-C character range

Parameter description:-D: the delimiter that follows and is used with-f. -F: cut a piece of information into a book Segment Based on the delimiter of-D, and use-F to get the meaning of the segment;-C: Take character (characters) take out a fixed character range in units.

Instance:

1. Retrieve the 3rd paths of the PATH variable:

Echo $ PATH | cut-d': '-F 5

2. Extract the 3rd to 5 paths of the PATH variable:

Echo $ PATH | cut-d': '-F 3-5

3. Retrieve the 3rd and 5th paths of the PATH variable:

Echo $ PATH | cut-d': '-F 3,5

4. Cut off the first 12 characters of each row in the output result of the export:

Export | cut-C 12-

Grep command

Grep's advanced usage of regular expressions is not involved here.

The basic usage is as follows:

Grep [-acinv] [-- color = auto] 'query string' filename

-A: Search for data from binary files in TXT files.

-C: calculates the number of times a 'query string' is found.

-I: case insensitive

-N: Output row number

-V: reverse selection, that is, the row without the 'search string' content is displayed.

-- Color = Auto: You can add the color of the keywords to display them. Generally, the operating system uses aliasgrep = 'grep-color = auto' by default'

Instance:

1. Find the row where reboot is located in last:

Last | grep 'reboot'

2. Reverse Selection:

Last | grep-V 'reboot'

Sort command

Sort [-fbmnrtuk]

-F: Ignore the case sensitivity differences. This is weird, not-I. It is found after you find the help: foldlower case to upper case characters.

-B: Ignore the leading space character.

-M: sort by month name

-N: Use "pure numbers" for sorting

-R: reverse sorting

-U: uniq. Only one row is displayed in the same data.

-T: separator, Tab by default

-K: The range in which the data is sorted.

Instance:

1. Sorting of personal accounts:

CAT/etc/passwd | sort

2. sort by the third column:

CAT/etc/passwd | sort-t': '-K 3

3. sort by numbers in three columns:

CAT/etc/passwd | sort-t': '-K 3-N

4. truncate the last Output account and sort it:

Last | cut-D ''-F 1 | sort

WC command

Usage:

WC [-lwn]

-L: only list rows.

-W: How many words are listed (English words)

-N: the number of characters.

Instance:

1. Calculate the number of characters in/etc/manpath. config.

CAT/etc/manpath. config | WC

2. calculate the total number of Logon systems in this month:

Last | grep [A-Za-Z] | grep-V 'wtmp' | WC-l

Uniq command

Used to display duplicate data only once.

Uniq [-ic]

-I: case insensitive

-C: Count

Instance:

1. Use last to list accounts. Only the account column is retrieved. After sorting, only one digit is output.

Last | cut-D ''-F 1 | sort | uniq

2. Calculate the number of logins:

Last | cut-D ''-F 1 | sort | uniq-C