1.11 Locating and Searching Files Flashcards
2
Q
What is the advantage of using the locate utility over the find utility? What are the disadvantages?
A
- Advantage: the locate utility is much faster because it searches through a pre-built index of all the files in the filesystem, whereas the find utility physically walks through each directory looking for the criteria you specify
- Disadvantages: (a)the index has to be built and/or updated with the latest information before the command can be used, (b)index creation can take a long time and consume a lot of system resources, (c)the locate command is not as versatile or flexible as the find command, (d)the locate command is not installed by default on most systems.
3
Q
When would you use the which command to locate a file?
A
Use the which command to display the full path to a particular shell command or utilty. It is not use to locate other kinds of files.
4
Q
Which utilities can you use to locate a file?
A
- find
- locate
- whereis
- which
5
Q
Which utilities can you use to locate and get information about a command?
A
Use the whereis command to locate and get information about a command.
6
Q
What does it mean when a command is hashed?
A
When a command is hashed, it is in the shell’s hash table, which means the command command has been used recently.
7
Q
How can you discover the category of a command?
A
Use the type command to discover the category of a command - what kind of command you are dealing with.
8
Q
What commands can you use to search for text within files?
A
Use the grep (or egrep or fgrep) command to search for text within files.
9
Q
How do you configure the system to use the locate command?
A
- Install the package containing the locate utility - findutils-locate
- Generate the index, /var/log/locatedb, using the updatedb command
10
Q
What does the find command do?
A
Searches through all files (based on the file system) by name, file size, time created, and other options.
11
Q
What does the -name option of the find command do?
A
The -name option locates a file or directory by name in a specific path. When using this option, enclose string arguments in single quotes and use wildcards for partial names.
12
Q
What does the -iname option of the find command do?
A
The -iname option locates a file or directory by name in a specific path, like the -name option, but matching is not case-sensitive.
13
Q
What does the -user option of the find command do?
A
The -user option finds files owned by a specific user.
14
Q
What does the -size option of the find command do?
A
The -size option finds files of a specific size. Use the following options:
15
Q
Which argument modifiers can be used with the -size option of the find command?
A
- c specifies the file size in bytes
- k specifies the file size in kilobytes
- M specifies the file size in megabytes
16
Q
What does the -mtime option of the find command do?
A
The -mtime option finds files last modified before or after a specified number of days ago.
17
Q
What does the -type option of the find command do?
A
The -type option specifies whether to find files or directories. The f argument specifies files, and the d argument specifies directories.
18
Q
What does the -maxdepth option of the find command do?
A
The -maxdepth option specifies how many directory levels down to search.
19
Q
What does the -print0 option of the find command do?
A
The -print0 option finds filenames with spaces.
20
Q
What does the -o parameter of the find command do?
A
The -o parameter specifies a logical OR between options when searching with multiple criteria.
21
Q
What does specifying . as the directory argument of the find command do?
A
Specifying . as the directory argument causes find to search the current directory and all subdirectories.
22
Q
What does the locate command do?
A
Search an index file for specific parameters.
23
Q
What are the main features of the locate command?
A
- Much faster than find.
- Uses /var/log/locatedb as the index file for searches.
- Uses the updatedb command to update the file index. The configuration file for updatedb is /etc/updatedb.conf
- Searches from the root (/) directory if no path is specified.
- Finds all files that contain the specified string without using wildcards.
- Does not, by default, verify that the file exists if its file index is outdated.
- Does not display files created after the last time the file index was updated.
- Does not search for files by attribute.
24
Q
Where is the index file used by the locate command to conduct searches?
A
The locate command uses /var/log/locatedb as the index file when conducting searches.
25
Q
How do you update the index file used by the locate command after file system changes?
A
The updatedb command updates the index used by locate to conduct searches.
26
How does the **-c**option modify the behavior of the **locate** command?
**locate -c** counts the number of entries rather than list them.
27
How does the **-e**option modify the behavior of the **locate** command?
**locate -e** lists files only after verifying that they exist.
28
How does the **-i**option modify the behavior of the **locate** command?
**locate -i** ignores case.
29
How does the **-l**option modify the behavior of the **locate** command?
**locate -l** limits the number of files listed.
30
How does the **-b**option modify the behavior of the **locate** command?
**locate -b** searches for the string in only file or directory base names.
31
What does the **which** command do?
Displays the path to a command and determines whether a package is installed.
32
What does the **whereis** command do?
Displays the path to the binary files, the manual pages, and the source code. With no options, **whereis** show all available data.
33
What does the command **whereis -b** do?
**whereis -b** lists the path to the binary file (similar to **which**).
34
What does the command **whereis -m** do?
**whereis -m** lists the path to the man page files.
35
What does the command **whereis -s** do?
**whereis -s** lists the location of the source code.
36
What does the command **whereis -u** do?
**whereis -u** lists entries that do not have source code, binary file, and **man** page locations.
37
What does the **type** command do?
**type** displays the category of the command. Possible categories include:
38
What are possible categories for the **type** command?
* A built-in shell command
* A command that the shell calls (external command)
* An aliased command
* A function
* *Note**: If a called command has been used recently, the output says that the command is hashed, which means that it is in the shell's hash table.
39
What does the comand **find /user/home -name '\*.txt'** do?
**find /user/home -name '\*.txt'** finds all plain text files in the /user/home directory.
40
What does the comand **find / -name '\*paper\*'** do?
**find / -name '\*paper\*'** looks through the entire directory for any folder or directory name with the term paper in it, such as **termpaper.odt** or **wallpaper.jpg**.
41
What does the comand **find /user/home -size -300k** do?
**find /user/home -size -300k** finds all files in the **/user/home** directory smaller than 300K.
42
What does the comand **find /user/home -size +300k** do?
**find /user/home -size +300k** finds all files in the **/user/home** directory larger than 300K.
43
What does the comand **find /user/home -mtime -5** do?
**find /user/home -mtime -5** finds all files in the **/user/home** directory modified within the last five days.
44
What does the comand **find / -type f -name '\*paper\*'** do?
**find / -type f -name '\*paper\*'** finds only files with the string *paper* in the name.
45
What does the comand **find / -type d -name '\*paper\*'** do?
**find / -type d -name '\*paper\*'** finds only directories with the string *paper* in the name.
46
What does the comand **find -maxdepth 3 / -name '\*.txt'** do?
**find -maxdepth 3 / -name '\*.txt'** finds text files three directory levels down from the root directory.
47
What does the comand **find -print0 -name '\*.txt'** do?
**find -print0 -name '\*.txt'** finds **myreport.txt** and **my report.txt**. Without the **-print0** option, **my report.txt** is not listed.
48
What does the comand **updatedb** do?
**updatedb** updates the index file, **/var/log/locatedb**.
49
What does the comand **locate /user/home paper** do?
**locate /user/home paper** locates all files with the string *paper* as any part of the file name or directory path under the **/user/home** directory.
50
What does the comand **locate lib** do?
**locate lib** locates all files with the string *lib* anywhere in the file name or directory path.
51
What does the comand **locate -c lib** do?
**locate -c lib** counts the number of files with the string *lib*.
52
What does the comand **locate -e .odt** do?
**locate -e .odt** verifies that all **.odt files listed in the file index actually exist before it lists them.**
53
What does the comand **locate -i LibraryFines.csv** do?
**locate -i LibraryFines.csv** finds the **libraryfines.csv** file regardless of case.
54
What does the comand **locate -l 25 lib** do?
**locate -l 25 lib** lists only the first 25 files from the file index that contain the string *lib*.
55
What does the comand **locate -b lib** do?
**locate -b lib** displays **/var/lib** and **/user/home/libraryfines.csv** but not **/var/lib/usbutils/usb.ids**.
56
What does the comand **which ls** do?
**which ls** shows the path to the **ls** binary (executable) file.
57
What does the comand **which photorec** do?
**which photorec** shows the path to the **photorec** binary file if *photorec* is installed. If the command does not display a path, then the *photorec* utility is not installed.
58
What does the comand **whereis -m -u \*** do?
**whereis -m -u \*** lists all entries that have no **man** page location.
59
What does the comand **type cd** do?
**type cd** displays **cd** is a shell built-in.
60
What does the comand **type more** do?
**type more** displays the path to the binary file for **more**.
61
What does the **grep** command do?
The **grep** command searches through file text for specific words or character patterns.
62
What does the **-A *number*** option of the **grep** command do?
**grep -A *number*** prints a specified number of lines following the matching lines.
63
What does the **-a** option of the **grep** command do?
**grep -a** searches binary (executable) files as though they were text files.
64
What does the **-B *number*** option of the **grep** command do?
**grep -B *number*** prints a specified number of lines before the matching lines.
65
What does the **-C *number*** option of the **grep** command do?
**grep -C *number*** prints a specified number of lines of context around the matching lines.
66
What does the **-c** option of the **grep** command do?
**grep -c** shows the number of matches of the string for the file.
67
What does the **-E** option of the **grep** command do?
**grep -E** uses regular expressions for the text pattern.
68
What does the **-e *pattern*** option of the **grep** command do?
**grep -e *pattern*** specifies a literal pattern.
69
What does the **-f *file\_name*** option of the **grep** command do?
**grep -f *file\_name*** searches for multiple strings using a file that lists the string patterns.
70
What does the **-F** option of the **grep** command do?
**grep -F** uses a file as the source for the string patterns.
71
What does the **-i** option of the **grep** command do?
**grep -i** ignores the case of the string.
72
What does the **-l** option of the **grep** command do?
**grep -l** lists just the names of the files with a match.
73
What does the **-m *number*** option of the **grep** command do?
**grep -m *number*** shows only a specified number of matches for a file.
74
What does the **-n** option of the **grep** command do?
**grep -n** displays the line number of the lines containing the term.
75
What does the **-r** option of the **grep** command do?
**grep -r** searches the directory and all sub-directories for files containing the term.
76
What does the **-v** option of the **grep** command do?
**grep -v** displays non-matching lines.
77
What does the **--include=*file\_name*** option of the **grep** command do?
**grep --include=*file\_name*** searches only in files with names that match a specified string.
78
What does the **--exclude=*file\_name*** option of the **grep** command do?
**grep --exclude=*file\_name*** searches in files with names that do not match a specified string.
79
What does the **-w** option of the **grep** command do?
**grep -w** searches for whole words only.
80
What does the **egrep** command do?
The **egrep** command, like **grep**, searches through file text for specific words or character patterns, but allows regular expressions in the search strings. Uses the same options and syntax as **grep** and is identical to **grep -E**.
81
What does the regular expression pattern **^** do?
**^** matches terms that occur at the beginning of a line.
82
What does the regular expression pattern **$** do?
**$** matches terms that occur at the end of a line.
83
What does the regular expression pattern **\\<** do?
**\\<** matches words that begin with the term.
84
What does the regular expression pattern **\\>** do?
**\\>** matches words that end with the term.
85
What does the regular expression pattern **[asdf]** do?
**[asdf]** matches any one of the characters in the brackets.
86
What does the regular expression pattern **[0-9]** do?
**[0-9]** matches any of the range of numbers 0-9.
87
What does the regular expression pattern **[^xyz]** do?
**[^xyz]** omits any one of the letters in the list
88
What does the regular expression pattern **.** do?
**.** matches any single character.
89
What does the regular expression pattern **[asdf]+** do?
**[asdf]+** matches one or more of the characters in the list.
90
What does the regular expression pattern **\*** do?
**\*** matches any number, or none of the preceding single character
91
What does the regular expression pattern **|** do?
**|** matches either of the terms.
92
What does the regular expression pattern **\*c*** do?
**\** displays the literal value of a character used for expressions.
93
What does the regular expression pattern **()** do?
**()** groups expressions.
94
What does the **fgrep** command do?
The **fgrep** command, like **grep**, searches through file text for specific words or character patterns, but searches only for fixed strings, not wildcards or regular expressions, and is much faster than **grep**. Uses the same options and syntax as **grep** and is identical to **grep -F**.
95
What does the command **grep -A 3 Midway ~/docs/WWII-report** do?
**grep -A 3 Midway ~/docs/WWII-report** searches **WWII-report** for the pattern *Midway* and prints the line and the next three lines.
96
What does the command **grep -a var11 /bin** do?
**grep -a var11 /bin** searches all files, including binary files, in the **/bin** directory for the pattern *var11*.
97
What does the command **grep -c 3 Midway ~/docs/WWII-report** do?
**grep -c 3 Midway ~/docs/WWII-report** shows only the number of times the pattern *Midway* is found in the **WWII-report** file.
98
What does the command **grep -e '--count' ~/docs/doc1** do?
**grep -e '--count' ~/docs/doc1** looks for the pattern *--count* in the **doc1** file rather than interpreting it as an option.
99
What does the command **grep -l -r Midway ~/docs** do?
**grep -l -r Midway ~/docs** shows the name of all files in the **/home/user/docs** directory that contain the term *Midway*.
100
What does the command **grep -m 2 battle ~/docs/WWII-report** do?
**grep -m 2 battle ~/docs/WWII-report** shows only the first two times the term *battle* is found in the file.
101
What does the command **grep -n -i customVariable1 ~/java/program1.java** do?
**grep -n -i customVariable1 ~/java/program1.java** shows the line numbers of lines that have the term *customVariable1* in the **program1.java** file. This is case insensitive.
102
What does the command **grep -r battle ~/docs/** do?
**grep -r battle ~/docs/** searches the directory and all sub-directories for the term *battle*.
103
What does the command **grep -w tank ~/docs/WWII-report** do?
**grep -w tank ~/docs/WWII-report** searches only for the whole word *tank* in the file.
104
What does the command **egrep ^FAILURE ~/error\_logs** do?
**egrep ^FAILURE ~/error\_logs** matches the term *FAILURE* when it is at the beginning of the line in **error\_logs**.
105
What does the command **egrep tty7$ ~/.bash\_history** do?
**egrep tty7$ ~/.bash\_history** matches the term *tty7* when it is at the end of the line.
106
What does the command **egrep \** do?
**egrep \** matches all words or strings that begin with *are*. This includes *are*, *area*, and *arena*.
107
What does the command **egrep \\>are ~/myfile** do?
**egrep \\>are ~/myfile** matches all words or strings that end with *are*. This includes *areI*, *hare*, and *aware*.
108
What does the command **egrep watche[ds] ~/myfile** do?
**egrep watche[ds] ~/myfile** matches either *watched* or *watches*.
109
What does the command **egrep exhibit[0-9] ~/myfile** do?
**egrep exhibit[0-9] ~/myfile** matches *exhibit1*, *exhibit3*, or *exhibit8*.
110
What does the command **egrep [^Xx]mas ~/myfile** do?
**egrep [^Xx]mas ~/myfile** matches *Christmas* but not *xmas* or *Xmas*.
111
What does the command **egrep .are ~/myfile** do?
**egrep .are ~/myfile** matches *hare* and *care*, but not *aware* or *are*.
112
What does the command **egrep file[0-9]+ ~/myfile** do?
**egrep file[0-9]+ ~/myfile** matches *file0*, *file10*, and *file15636*.
113
What does the command **egrep fil\* ~/myfile** do?
**egrep fil\* ~/myfile** matches *fil*, *filll*, and *fillllllllllllllll*.
114
What does the command **egrep fil.\* ~/myfile** do?
**egrep fil.\* ~/myfile** matches *file*, *fill*, *file102*, and *filings*.
115
What does the command **egrep men|women ~/myfile** do?
**egrep men|women ~/myfile** matches *men* or *women*.
116
What does the command **egrep Hello\? ~/myfile** do?
**egrep Hello\? ~/myfile** matches *Hello?*.
117
What does the command **fgrep Midway Nimitz ~/docs/myfile** do?
**fgrep Midway Nimitz ~/docs/myfile** searches **myfile** for lines containing *Midway* or *Nimitz*.
