# Bash Command man pages. # VI/VIM #### Line Numbers vim can display line numbers using the below command: ``` :set number ``` ##### Skip to specific line number To skip to line 255: ``` :255 ``` ------------------------------------------------------------------------------------------------------------------------------------------ ##### Searching strings To search for a string in a text file, the / option can be used. In the below example, we're searching for the word test ``` :/test ``` To skip to the next found instance of the word, press the n key. ##### Search string on a range of lines In this example, I'm searching for the string 'test' on lines 1-100: ``` :1,100/test ``` ------------------------------------------------------------------------------------------------------------------------------------------ #### Deleting Lines Vim can delete lines using a number of methods ##### Remove X amount of lines. The below command would remove 5 lines from (and including) the current line: ``` :5d ``` ##### Remove a range of lines: ``` 1,5d ``` ------------------------------------------------------------------------------------------------------------------------------------------ #### Search and replace ##### Search and replace a word through the whole file: ``` :%s/wordtosearch/wordtoreplacewith ``` ##### Search and replace on specific lines We can couple the search and replace function of vim with the line number range tool. The below would find any instances of the word 'test' within the line range of 1-100, and then replace all instances of the word with 'testing': ``` :1,100s/test/testing ``` ------------------------------------------------------------------------------------------------------------------------------------------ #### Copy & pastse ##### Copy the currently selected line ``` :yy ``` ##### Copy a range of lines The below would copy lines 1-1000 ``` :1,1000y ``` ##### Paste the line: ``` p ``` ------------------------------------------------------------------------------------------------------------------------------------------ #### Saving & exiting ##### save and quit: ``` :wq ``` ##### don't save and quit ``` :q! ``` ##### Save as new file ``` :w newfilename ``` ------------------------------------------------------------------------------------------------------------------------------------------ # Find, Locate, and Grep ==================================================================================== ### FIND Find is a linux search tool that can be used to find a variety of files based on the given criteria. ------------------------------------------------------------------------------------------------------------------------------------------------ ##### Basic find find targetdirectory -name stringtofind ``` find / -name hello.txt ``` ##### wildcards ``` find / -name "*.txt" ``` ##### Discard errors (ie permission denied) ``` find / -name "*.txt" 2>/dev/null ``` ------------------------------------------------------------------------------------------------------------------------------------------------ ##### Find files with specific permissions Find files with read,write, and execute permissions ``` find / -perm +rwx ``` ------------------------------------------------------------------------------------------------------------------------------------------------ ##### Find files by size Find files that are greater than 2MB: ``` find / -size +2M ``` Find files that are less than 2MB: ``` find / -size -2M ``` Find files that are exactly 2MB: ``` find / -size 2M ``` ------------------------------------------------------------------------------------------------------------------------------------------------ ##### Find files by owner/group Find files based on group ``` find / -group groupname ``` Find files based on owner ``` find / -user username ``` ==================================================================================== ### LOCATE Locate is similar to find in its functionality, however, there are some important distinctions: - Locate keeps it's own database of files on a system - Locate is less disk IO intensive since it doesn't have to scan the whole hard drive for files, instead it references it's own database. - Locate isn't installed by default on most systems, the package name is mlocate. Once installed, you'll need to run the updated command to update locate's database - this should really be updated every time you use the command ------------------------------------------------------------------------------------------------------------------------------------------------ ##### Locate file based on name ``` locate test.txt ``` ==================================================================================== ### GREP ------------------------------------------------------------------------------------------------------------------------------------------------ ##### -i - case insensitive As with all of Linux, grep is case sensitive. The -i flag can be passed to ignore case type. ------------------------------------------------------------------------------------------------------------------------------------------------ ##### -v -exclude string The -v flag is used to exclude a string from an output. ------------------------------------------------------------------------------------------------------------------------------------------------ ##### | - or statement The below will search for string1 or string2 within a file, if both are found then both will be outputted. ``` grep 'string1|string2' filename ``` ------------------------------------------------------------------------------------------------------------------------------------------------ ##### -r - search files recursively ``` grep -r hello / ``` ------------------------------------------------------------------------------------------------------------------------------------------------ ##### -A & -B (before and after) Sometimes you might want to search for a string, and see the lines before/after that string. The below will show the 2 lines following the string ``` grep -A2 string filename ``` The below will show the 2 lines before the string ``` grep -B2 string filename ``` You can also combine these to see the lines before and after ``` grep -A2 -B2 string filename ``` ==================================================================================== #### -E or egrep - extended regular expression Regular expression is essentially the methodology that we can use to manipulate grep to find advanced string patterns. ------------------------------------------------------------------------------------------------------------------------------------------------ ##### Special characters When trying to grep for special characters, you need to make sure to 'escape' those characters, this is done by proceeding special characters with a \\: ``` grep -E year\'s ``` ------------------------------------------------------------------------------------------------------------------------------------------------ ##### Beginning and end of line line begins with The below example would show any lines beginning with the character '1' ``` grep -E "^1" filename ``` line ends with The below example would show any lines ending with the character '1' ``` grep -e "1$" filename ``` ------------------------------------------------------------------------------------------------------------------------------------------------ ##### Ranges grep interprets ranges that are defined through square brackets \[\]. line begins with 1 and is followed by numbers in the 0-2 range: ``` grep -E "^1[0-2]" filename ``` We can also search for ranges of letters The below command would search for the letter b, proceeded by any letter in the specified range, followed by the letter g: ``` grep -E "b[aeiou]g" filename ``` We can also search a range of letters like this: ``` grep -E "b[a-z]g" filename ``` You can also combine ranges ``` grep -E "b[a-z,A-Z]g" filename ``` ------------------------------------------------------------------------------------------------------------------------------------------------ ##### Wildcards There are a number of wildcard options available to use in egrep. . - any single character ``` grep -e "c.t" filename ``` - Matches: "cat", "cot", "cut", etc. - Does not match: "ct", "caat" \* - matches zero or more occurrences of the preceding character ``` grep -e "g*d" filename ``` - Matches: "gd", "god", "good", "goood" - Does not match: "go", "goooo", "gdo", "goddy" .\* - match zero or more of any character ``` grep -e "a.*b" filename ``` - Matches: "ab", "acb", "axyzb", "a123b" - Does not match: "a b", "ab ", "acbd", "a" ------------------------------------------------------------------------------------------------------------------------------------------------