A commonly used simple tools
cat [OPTION]... [FILE]...
- -E: $ display line terminator
- -n: to show each line are numbered.
- -A: show all control characters
- -s: compressed air conduct continuous line
more: Paging File View
-d: display the page and quit tips
less: page after page to view the output file or STDIN
When you view useful commands include:
/ Text search text
n / N skip to the next or previous match
less command is a command to use pager man
Text cut cut [OPTION] ... [FILE] ...
- -f: take the first few fields
- -c: cutting by character
- -d: Specifies the cut, default is tab
wc text statistics
- -l: counting only the number of rows
- -w: world, only to calculate the total number of words
- -c: Total number of bytes calculated only
- -m: just calculate the total number of characters
- -L: shows the length of the longest line in the file
sort, sort text
- -r: reverse output
- -R: random ordering
- -n: digital execution order by size
- Ignore character case options (fold) string: -f
- -u: delete duplicate rows in the output
- c -tc used as delimiter field
- -k X X column using c options as split fields can be used to organize multiple times
uniq statistical tools
- -c: Displays the number of each row recurring
- -d: show only duplicate rows
- -u: do not display duplicate rows
- Often used in conjunction with and sort commands: sort userlist.txt | uniq -c
grep text filtering
Line to match the print; text search tool, based on user-specified "model" for the target text line by line matching check: the role of
grep [OPTIONS] PATTERN [FILE...]
- -m #: # times after the match to stop
- -v: display pattern is not matched to the line
- -i: ignore case
- The number of rows to the match statistics: -c
- -o: to display only matching rows
- -q: silent mode does not output any information
- -A #：after后#hang
- -B #: before, before the line #
- -C #: context, each longitudinal row #
- -e: between the reality of multiple options or relationship grep -e 'cat' -e 'dog' file
- -w: match whole words
- -E: Use ERE
- -F: the equivalent of fgrep, does not support regular expressions
- -f: file based on file processing mode
REGEXP: Regular Expressions, a special kind of mode character and text written characters, some characters (metacharacters) does not represent a character literal meaning, while a control function or wildcard
Program support: grep, sed, awk, vim, less, nginx, varnish, etc.
Divided into two categories: basic regular expressions: BRE, extended regular expression: ERE
Basic regular expression metacharacters
- . Matches any single character
- [] Match any single character within a specific range, columns formula: [li] [wang] [0-9]
- Any single character [^] matches outside the specified range
- [: Alnum:] characters and letters
- [: Alpha:] stands for any English uppercase and lowercase characters, az, AZ
- [: Lower:] lowercase letters [: upper:] uppercase letters
- [: Blank:] blank characters, spaces, tabs, etc.
- [: Space:] vertical and horizontal whitespace (ratio [: blank:] contains a wide range)
- [: Cntrl:] uncontrollable printed character (backspace, delete, bell ...
- [: Digit:] decimal number [: xdigit:] hexadecimal digits
- [: Graph:] non-blank printable characters
- [: Print:] printable characters
- [: Punct:] Punctuation
- * Matches any number of times in front of the characters, including zero greedy mode: as long as possible match
- * Any character of any length
- \? Match its preceding character 0 or 1 times
- \ + Matches its preceding character at least once
- \ {N \} matches the preceding character n times
- \ {M, n \} foregoing character matches at least m times, n times at most
- \ {, N \} foregoing character match up n times
- \ {N, \} foregoing character match at least n times
Location anchoring: positioning to appear
- ^ Beginning of a line anchored mode for most of the left
- $ Anchored end of the line, for the rightmost pattern
- ^ PATTERN $ pattern matching for the whole line
- ^ $ Empty line
- ^ [[: Space:]] * $ Blank lines
- \ <Or \ b word-initial anchor for word patterns of the left
- \> Or \ b anchor ending, the right mode for the word
- \ <Pattern \> matches the entire word
Grouping and references
Packet: \ (\) of one or more characters tied together, as a whole process, such as: \ (root \) \ +
Packet parentheses pattern matching content to be recorded in the regular expression engine of internal variables, these variables are named: \ 1, \ 2 \ 3, ...
\ 1 showing from the left a first mode between the left bracket and a right bracket matching the matched character
Example: \ (string1 \ (string2 \) \)
\1 ：string1\(string2\)
\2 ：string2
Backward references: character reference foregoing matched parentheses packet mode, rather than the pattern itself
Or: \ |
Example: a \ | ba or b
C \ | cat C or cat
\(C\|c\)at Cat或cat