Linux Wildcards

• "?": Matches any single character
  Pay special attention to the emphasis on "single", that is to say, a "?" represents any single character that must exist. These characters can be letters or symbols or numbers, such as "?a" can match "3a" or "Ha" or "(a", etc.
  
  example:

  $ ls /dev/ram?? ← List "/dev/ram" followed by any two characters of files /dev/ram10 /dev/ram11 /dev/ram12 /dev/ram13 /dev/ram14 /dev/ram15 $ cd /bin ← Enter the directory /bin $ ls l? ← List the files whose first word is "l" (lowercase L) and the second word is any single character ln  ls $ ls ?o?? ← List the 1st, 3rd, and 4th characters as any character, and the 2nd word is "o" files more  sort $ ls ??? ← List the files with length=3 awk  cat  cut  env  pwd  red  rpm  rvi  sed  tar $ ls ?ed ← list the first word as any character, followed by "ed" file red  sed

  
  Wildcards can be used with almost any file-related command.
  
  example:
  

  $ mv l? /tmp $ cp ch?.html /backup $ rm ???.txt

  
  
• "*": Matches zero or more characters of any length
  Pay special attention to emphasizing that "none" is also counted, that is to say, a "*" means nothing to a string of any length. For example, "y*" can match "y" or "ya", "yes", "yahoo@tw" and so on.
  
  example:
  

  $ ls /dev/ram* ← List "/dev/ram" followed by a string of any length /dev/ram /dev/ram10 /dev/ram13 /dev/ram2 /dev/ram5 /dev/ram8 /dev/ram0 /dev/ram11 /dev/ram14 /dev/ram3 /dev/ram6 /dev/ram9 /dev/ram1 /dev/ram12 /dev/ram15 /dev/ram4 /dev/ram7 /dev/ramdisk $ cd /etc  ← Enter the directory /etc $ ls -d c*/ ←list the directories starting with "c" and followed by any name directory cron.d/  cron.daily/  cron.hourly/  cron.monthly/  cron.weekly/  cups/ $ ls *.cfg ←List all files with the extension name "cfg" (the file name after "." is the extension name) a2ps.cfg  a2ps-site.cfg  enscript.cfg $ ls -d *-* ←List all files with "-" in the file name(the first or last character of the file name is "-" will also be established) a2ps-site.cfg      gnome-vfs-mime-magic  jvm-commmon     shadow- bonobo-activation  gpm-root.conf         lsb-release.d   system-release dbus-1             group-                passwd- fedora-release     gshadow-              redhat-lsb gnome-vfs-2.0      gtk-2.0               redhat-release $ ls s*s ← list "s "All files beginning and ending with services  shells  sudoers

  
  Although the wildcard "*" can match anything, it will exclude hidden files starting with the character "." Usage is summarized as follows:

  wildcards	matching profile	example
  *	Any file. Except hidden files at the beginning of "."	ls *
  *.*	Any file name with ".", such as "readme.txt", "abc.", etc. but not including the file at the beginning of ".", such as ".Trash"	cp *.* /tmp
  .*	Any hidden file	rm .*
  .*/	Any hidden directory ("/" is the directory at the end of the file name, and it will appear with ls -p or ls -F )	ls .*/
  */	Any directory, but does not include hidden directories starting with "."	mv */ /tmp

  
  例:
  

  $ ls -d .*/ ←List only hidden directories $ ls -d .* ←List only hidden files $ rm *. ←Delete only hidden files $ rm -rf * ←Delete all files and directories in the working directory, But does not include hidden files $ rm -r */ ← Delete all directories in the working directory, but does not include files and hidden directories

  
  Since "*" is insatiable in matching files, it is very convenient and dangerous to use. It is recommended to use wildcards to operate rm , mv and other commands before using ls to confirm the matching, so as not to accidentally delete files by mistake.
  
  From these examples, you should be able to feel the flexibility of the text interface and the power of nuclear bombs. To give my own example, although I usually use Windows as my work platform, when backing up files, I obediently use the Windows "Command Prompt" (Command Prompt), that is, use the Windows text interface with wildcards To filter the files to be backed up, although the function of the text interface of Windows is not as good as one-tenth of that of Linux, it is also more convenient than using the mouse to select one by one in the graphical operation.
  
• "{PATTERN 1,PATTEN 2,..,PAATER n}" : Expands to multiple patterns
  Enclosed in curly braces "{ }", within which are separated patterns by ",", and each pattern is expanded separately.
  
  example:
  

  $ echo iphone{3g,5,5c}, ← expand to list "3g", "5", and "5c" iphone3g, iphone5, iphone5c, $ echo iphone {3g,5,5c} , ← before and after "{ }" There is a difference in the output of characters with or without spaces. When there are spaces, the characters before and after the characters will not be expanded iphone 3g 5 5c , $ ls -d {.*,.*/} ← only list hidden files and hidden directories $ rm -fr {.*/,.*,*} ←Delete all files in the working directory, including hidden files and hidden directories (dangerous action) $ cp -v /bin/{*ee*,*dd*} /tmp Copy files matching wildcard patterns "*ee*" and "*dd*" `/bin/sleep' -> `/tmp/sleep' `/bin/usleep' -> `/tmp/usleep' `/bin/dd' -> `/tmp/dd'

  
  
• "[ ]" : Specifies a character set to match against
  characters in "[ ]" represent the character set to be matched. Its usage is similar to that of " ? ", but any character range of "?" Too wide, and this usage narrows its range, and the characters within the range are collected into "[ ]".
  For example, "analy[zs]e" means that it can match "analyse" or "analyze". Another example "ID[abc]123" can match "IDa123" or "IDb123" or "IDc123" but not "IDabc123", because "[ ]" contains more than one character just match one of the matching characters.
  
  example:
  

  $ ls /dev/tty[14] ←list the files of tty1 or tty4 in the "/dev" directory /dev/tty1   /dev/tty4 $ ls /dev/tty[123][45] /dev/tty14  /dev/tty15  /dev/tty24  /dev/tty25  /dev/tty34  /dev/tty35 $ ls /dev/l[op]? /dev/log    /dev/lp0    /dev/lp1    /dev/lp2    /dev/lp3

  
  

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• "[ - ]" : Specifies a range of characters to match
  In many cases, if a character set is used to match a template "AD 199[012345]" that has a sequence such as wildcards, it can be expressed as "AD 199[0-5]" in a range.
  The ranges are separated by "-", and there can be no space between characters and "-". But special attention must be paid to the matching range from small to large. If the system does not set locales, the order principle is based on the size of the ASCII code [Note]. However, the sorting of loocales may be different if there is a setting. Taking "en_US.UTF-8" encoding as an example, its sequence rule is "0<1<2 ...<9< a <A <b <B ... z<Z" (the later one is bigger).
  
  If the matching screening range is not enough, you can always add it, such as [a-cA-C0-5]. Similar to the usage of character sets , no matter how much "[ ]" is written inside, it only represents one matching character. It is easier to understand clearly by looking at examples.
  
  例:

  $ LANG=en_US.UTF-8 ←Set the encoding of the locales to "en_US.UTF-8" (different locales results may be different) $ ls /usr/bin/t[b-Y]e ←list "t" and "e", the middle is the file between "b to Y" /usr/bin/tee  /usr/bin/tie   /usr/bin/toe $ ls /usr/bin/t[Y-b]e ← invalid representation, because The matching filter range must be from small to large ls: cannot access t[Y-b]e: No such file or directory $ ls /usr/bin/icc[7-9i-t1-2]* ←the 4th character, range From "7~9" or "i~t" or "1~2" as long as one of them is established /usr/bin/icc2ps  /usr/bin/icclink  /usr/bin/icctrans

  
  For example, when installing Linux, the option to choose the language to install is "English", and the encoding is "en_US.UTF-8". If the user chooses a different language, it may affect the sorting of wildcards. Therefore, please enter LANG=en_US.UTF-8 to use this encoding before the experiment. Otherwise the results may be different from the above tests.
  
  The effect of different encodings on the results is also the main shortcoming of wildcards, which can be overcome by using regular expressions .
  
  
• "[^ ]" or "[!]": Performs negation or inverse matching
  "[^]" = "[!]", most of the shells can accept both, which is the specified character or character range for reverse match.
  
  example:
  

  $ ls /dev/tty[!14] dev/tty0   /devtty3   /devtty6   /devtty8 dev/tty2   /devtty5   /devtty7   /devtty9 $ ls /usr/bin/t[!o-p]e /usr/bin/tee  /usr/bin/tie $ ls /usr/bin/icc[^2]* /usr/bin/icclink  /usr/bin/icctrans

  
  
• POSIX Character
  The modern version of wildcards also supports the same POSIX character set as the regular expression . The POSIX character set can simplify the description, such as "[:digit:]" to represent all numbers , is equivalent to the wildcard template "[0123456789]" or "[0-9]".
  
  Because the POSIX-character set is a subset of the square bracket notation "[ ]" introduced above (no matter how much "[ ]" is written in it, it only represents one of the matching characters), so the application needs to add square brackets Written as "[[:digit:]]".
  
  Commonly used POSIX character sets are as follows:
  

  POSIX Character matches characters
  POSIX	ASCII	Illustrate
  [:alnum:]	[A-Z,a-z,0-9]	English letters and numbers
  [:alpha:]	[A-Z,a-z]	Alphabet
  [:blank:]		Space(ASCII = 20H) and TAB(ASCII = 9H)
  [:cntrl:]	[0H-1FH,7FH]	Control character
  [:digit:]	[0-9]	Mumber
  [:graph:]	[21H-7EH]	Characters that will be displayed
  [:upper:]	[A-Z]	Uppercase letter
  [:lower:]	[a-z]	Lower case letters
  [:print:]	[20H-7EH]	Characters that will be displayed + spaces
  [:punct:]	[\]\[!"#$%&'()*+,./:;<=>?@\^_`{|}~-]	Punctuation and symbols
  [:space:]	[ \t\r\n\v\f]	Whitespace (characters not displayed)
  [:xdigit:]	[A-Fa-f0-9]	Character in hexadecimal

  
  In addition to simplifying the description, using the POSIX character set has another advantage that the result is not affected by the locales. For a more detailed description of the POSIX character set, please refer to POSIX Characters in regular representation .
  
  example:
  

  $ ls -d /etc/[[:upper:]]* ← List files whose first character is uppercase /etc/ConsoleKit  /etc/DIR_COLORS.xterm  /etc/Muttrc.local    /etc/PolicyKit /etc/DIR_COLORS  /etc/Muttrc            /etc/NetworkManager  /etc/X11

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