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