# 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" ------------------------------------------------------------------------------------------------------------------------------------------------