1.11 Locating and Searching Files

Question 2

What is the advantage of using the locate utility over the find utility? What are the disadvantages?

Answer 2

• 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.

Question 3

When would you use the which command to locate a file?

Answer 3

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.

Question 4

Which utilities can you use to locate a file?

Answer 4

• find
• locate
• whereis
• which

Question 5

Which utilities can you use to locate and get information about a command?

Answer 5

Use the whereis command to locate and get information about a command.

Question 6

What does it mean when a command is hashed?

Answer 6

When a command is hashed, it is in the shell’s hash table, which means the command command has been used recently.

Question 7

How can you discover the category of a command?

Answer 7

Use the type command to discover the category of a command - what kind of command you are dealing with.

Question 8

What commands can you use to search for text within files?

Answer 8

Use the grep (or egrep or fgrep) command to search for text within files.

Question 9

How do you configure the system to use the locate command?

Answer 9

1. Install the package containing the locate utility - findutils-locate
2. Generate the index, /var/log/locatedb, using the updatedb command

Question 10

What does the find command do?

Answer 10

Searches through all files (based on the file system) by name, file size, time created, and other options.

Question 11

What does the -name option of the find command do?

Answer 11

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.

Question 12

What does the -iname option of the find command do?

Answer 12

The -iname option locates a file or directory by name in a specific path, like the -name option, but matching is not case-sensitive.

Question 13

What does the -user option of the find command do?

Answer 13

The -user option finds files owned by a specific user.

Question 14

What does the -size option of the find command do?

Answer 14

The -size option finds files of a specific size. Use the following options:

Question 15

Which argument modifiers can be used with the -size option of the find command?

Answer 15

• c specifies the file size in bytes
• k specifies the file size in kilobytes
• M specifies the file size in megabytes

Question 16

What does the -mtime option of the find command do?

Answer 16

The -mtime option finds files last modified before or after a specified number of days ago.

Question 17

What does the -type option of the find command do?

Answer 17

The -type option specifies whether to find files or directories. The f argument specifies files, and the d argument specifies directories.

Question 18

What does the -maxdepth option of the find command do?

Answer 18

The -maxdepth option specifies how many directory levels down to search.

Question 19

What does the -print0 option of the find command do?

Answer 19

The -print0 option finds filenames with spaces.

Question 20

What does the -o parameter of the find command do?

Answer 20

The -o parameter specifies a logical OR between options when searching with multiple criteria.

Question 21

What does specifying . as the directory argument of the find command do?

Answer 21

Specifying . as the directory argument causes find to search the current directory and all subdirectories.

Question 22

What does the locate command do?

Answer 22

Search an index file for specific parameters.

Question 23

What are the main features of the locate command?

Answer 23

• 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.

Question 24

Where is the index file used by the locate command to conduct searches?

Answer 24

The locate command uses /var/log/locatedb as the index file when conducting searches.

Question 25

How do you update the index file used by the locate command after file system changes?

Answer 25

The updatedb command updates the index used by locate to conduct searches.

Question 26

How does the -coption modify the behavior of the locate command?

Answer 26

locate -c counts the number of entries rather than list them.

Question 27

How does the -eoption modify the behavior of the locate command?

Answer 27

locate -e lists files only after verifying that they exist.

Question 28

How does the -ioption modify the behavior of the locate command?

Answer 28

locate -i ignores case.

Question 29

How does the -loption modify the behavior of the locate command?

Answer 29

locate -l limits the number of files listed.

Question 30

How does the -boption modify the behavior of the locate command?

Answer 30

locate -b searches for the string in only file or directory base names.

Question 31

What does the which command do?

Answer 31

Displays the path to a command and determines whether a package is installed.

Question 32

What does the whereis command do?

Answer 32

Displays the path to the binary files, the manual pages, and the source code. With no options, whereis show all available data.

Question 33

What does the command whereis -b do?

Answer 33

whereis -b lists the path to the binary file (similar to which).

Question 34

What does the command whereis -m do?

Answer 34

whereis -m lists the path to the man page files.

Question 35

What does the command whereis -s do?

Answer 35

whereis -s lists the location of the source code.

Question 36

What does the command whereis -u do?

Answer 36

whereis -u lists entries that do not have source code, binary file, and man page locations.

Question 37

What does the type command do?

Answer 37

type displays the category of the command. Possible categories include:

Question 38

What are possible categories for the type command?

Answer 38

• 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.

Question 39

What does the comand find /user/home -name ‘*.txt’ do?

Answer 39

find /user/home -name ‘*.txt’ finds all plain text files in the /user/home directory.

Question 40

What does the comand find / -name ‘*paper*‘ do?

Answer 40

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.

Question 41

What does the comand find /user/home -size -300k do?

Answer 41

find /user/home -size -300k finds all files in the /user/home directory smaller than 300K.

Question 42

What does the comand find /user/home -size +300k do?

Answer 42

find /user/home -size +300k finds all files in the /user/home directory larger than 300K.

Question 43

What does the comand find /user/home -mtime -5 do?

Answer 43

find /user/home -mtime -5 finds all files in the /user/home directory modified within the last five days.

Question 44

What does the comand find / -type f -name ‘*paper*‘ do?

Answer 44

find / -type f -name ‘*paper*‘ finds only files with the string paper in the name.

Question 45

What does the comand find / -type d -name ‘*paper*‘ do?

Answer 45

find / -type d -name ‘*paper*‘ finds only directories with the string paper in the name.

Question 46

What does the comand find -maxdepth 3 / -name ‘*.txt’ do?

Answer 46

find -maxdepth 3 / -name ‘*.txt’ finds text files three directory levels down from the root directory.

Question 47

What does the comand find -print0 -name ‘*.txt’ do?

Answer 47

find -print0 -name ‘*.txt’ finds myreport.txt and my report.txt. Without the -print0 option, my report.txt is not listed.

Question 48

What does the comand updatedb do?

Answer 48

updatedb updates the index file, /var/log/locatedb.

Question 49

What does the comand locate /user/home paper do?

Answer 49

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.

Question 50

What does the comand locate lib do?

Answer 50

locate lib locates all files with the string lib anywhere in the file name or directory path.

Question 51

What does the comand locate -c lib do?

Answer 51

locate -c lib counts the number of files with the string lib.

Question 52

What does the comand locate -e .odt do?

Answer 52

locate -e .odt verifies that all .odt files listed in the file index actually exist before it lists them.

Question 53

What does the comand locate -i LibraryFines.csv do?

Answer 53

locate -i LibraryFines.csv finds the libraryfines.csv file regardless of case.

Question 54

What does the comand locate -l 25 lib do?

Answer 54

locate -l 25 lib lists only the first 25 files from the file index that contain the string lib.

Question 55

What does the comand locate -b lib do?

Answer 55

locate -b lib displays /var/lib and /user/home/libraryfines.csv but not /var/lib/usbutils/usb.ids.

Question 56

What does the comand which ls do?

Answer 56

which ls shows the path to the ls binary (executable) file.

Question 57

What does the comand which photorec do?

Answer 57

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.

Question 58

What does the comand whereis -m -u * do?

Answer 58

whereis -m -u * lists all entries that have no man page location.

Question 59

What does the comand type cd do?

Answer 59

type cd displays cd is a shell built-in.

Question 60

What does the comand type more do?

Answer 60

type more displays the path to the binary file for more.

Question 61

What does the grep command do?

Answer 61

The grep command searches through file text for specific words or character patterns.

Question 62

What does the -A number option of the grep command do?

Answer 62

grep -A number prints a specified number of lines following the matching lines.

Question 63

What does the -a option of the grep command do?

Answer 63

grep -a searches binary (executable) files as though they were text files.

Question 64

What does the -B number option of the grep command do?

Answer 64

grep -B number prints a specified number of lines before the matching lines.

Question 65

What does the -C number option of the grep command do?

Answer 65

grep -C number prints a specified number of lines of context around the matching lines.

Question 66

What does the -c option of the grep command do?

Answer 66

grep -c shows the number of matches of the string for the file.

Question 67

What does the -E option of the grep command do?

Answer 67

grep -E uses regular expressions for the text pattern.

Question 68

What does the -e pattern option of the grep command do?

Answer 68

grep -e pattern specifies a literal pattern.

Question 69

What does the -f file_name option of the grep command do?

Answer 69

grep -f file_name searches for multiple strings using a file that lists the string patterns.

Question 70

What does the -F option of the grep command do?

Answer 70

grep -F uses a file as the source for the string patterns.

Question 71

What does the -i option of the grep command do?

Answer 71

grep -i ignores the case of the string.

Question 72

What does the -l option of the grep command do?

Answer 72

grep -l lists just the names of the files with a match.

Question 73

What does the -m number option of the grep command do?

Answer 73

grep -m number shows only a specified number of matches for a file.

Question 74

What does the -n option of the grep command do?

Answer 74

grep -n displays the line number of the lines containing the term.

Question 75

What does the -r option of the grep command do?

Answer 75

grep -r searches the directory and all sub-directories for files containing the term.

Question 76

What does the -v option of the grep command do?

Answer 76

grep -v displays non-matching lines.

Question 77

What does the –include=file_name option of the grep command do?

Answer 77

grep –include=file_name searches only in files with names that match a specified string.

Question 78

What does the –exclude=file_name option of the grep command do?

Answer 78

grep –exclude=file_name searches in files with names that do not match a specified string.

Question 79

What does the -w option of the grep command do?

Answer 79

grep -w searches for whole words only.

Question 80

What does the egrep command do?

Answer 80

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.

Question 81

What does the regular expression pattern ^ do?

Answer 81

^ matches terms that occur at the beginning of a line.

Question 82

What does the regular expression pattern $ do?

Answer 82

$ matches terms that occur at the end of a line.

Question 83

What does the regular expression pattern \< do?

Answer 83

\< matches words that begin with the term.

Question 84

What does the regular expression pattern \> do?

Answer 84

\> matches words that end with the term.

Question 85

What does the regular expression pattern [asdf] do?

Answer 85

[asdf] matches any one of the characters in the brackets.

Question 86

What does the regular expression pattern [0-9] do?

Answer 86

[0-9] matches any of the range of numbers 0-9.

Question 87

What does the regular expression pattern [^xyz] do?

Answer 87

[^xyz] omits any one of the letters in the list

Question 88

What does the regular expression pattern . do?

Answer 88

. matches any single character.

Question 89

What does the regular expression pattern [asdf]+ do?

Answer 89

[asdf]+ matches one or more of the characters in the list.

Question 90

What does the regular expression pattern * do?

Answer 90

* matches any number, or none of the preceding single character

Question 91

What does the regular expression pattern | do?

Answer 91

| matches either of the terms.

Question 92

What does the regular expression pattern *c* do?

Answer 92

**** displays the literal value of a character used for expressions.

Question 93

What does the regular expression pattern () do?

Answer 93

() groups expressions.

Question 94

What does the fgrep command do?

Answer 94

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.

Question 95

What does the command grep -A 3 Midway ~/docs/WWII-report do?

Answer 95

grep -A 3 Midway ~/docs/WWII-report searches WWII-report for the pattern Midway and prints the line and the next three lines.

Question 96

What does the command grep -a var11 /bin do?

Answer 96

grep -a var11 /bin searches all files, including binary files, in the /bin directory for the pattern var11.

Question 97

What does the command grep -c 3 Midway ~/docs/WWII-report do?

Answer 97

grep -c 3 Midway ~/docs/WWII-report shows only the number of times the pattern Midway is found in the WWII-report file.

Question 98

What does the command grep -e ‘–count’ ~/docs/doc1 do?

Answer 98

grep -e ‘–count’ ~/docs/doc1 looks for the pattern –count in the doc1 file rather than interpreting it as an option.

Question 99

What does the command grep -l -r Midway ~/docs do?

Answer 99

grep -l -r Midway ~/docs shows the name of all files in the /home/user/docs directory that contain the term Midway.

Question 100

What does the command grep -m 2 battle ~/docs/WWII-report do?

Answer 100

grep -m 2 battle ~/docs/WWII-report shows only the first two times the term battle is found in the file.

Question 101

What does the command grep -n -i customVariable1 ~/java/program1.java do?

Answer 101

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.

Question 102

What does the command grep -r battle ~/docs/ do?

Answer 102

grep -r battle ~/docs/ searches the directory and all sub-directories for the term battle.

Question 103

What does the command grep -w tank ~/docs/WWII-report do?

Answer 103

grep -w tank ~/docs/WWII-report searches only for the whole word tank in the file.

Question 104

What does the command egrep ^FAILURE ~/error_logs do?

Answer 104

egrep ^FAILURE ~/error_logs matches the term FAILURE when it is at the beginning of the line in error_logs.

Question 105

What does the command egrep tty7$ ~/.bash_history do?

Answer 105

egrep tty7$ ~/.bash_history matches the term tty7 when it is at the end of the line.

Question 106

What does the command **egrep ** do?

Answer 106

**egrep ** matches all words or strings that begin with are. This includes are, area, and arena.

Question 107

What does the command egrep \>are ~/myfile do?

Answer 107

egrep \>are ~/myfile matches all words or strings that end with are. This includes areI, hare, and aware.

Question 108

What does the command egrep watche[ds] ~/myfile do?

Answer 108

egrep watche[ds] ~/myfile matches either watched or watches.

Question 109

What does the command egrep exhibit[0-9] ~/myfile do?

Answer 109

egrep exhibit[0-9] ~/myfile matches exhibit1, exhibit3, or exhibit8.

Question 110

What does the command egrep [^Xx]mas ~/myfile do?

Answer 110

egrep [^Xx]mas ~/myfile matches Christmas but not xmas or Xmas.

Question 111

What does the command egrep .are ~/myfile do?

Answer 111

egrep .are ~/myfile matches hare and care, but not aware or are.

Question 112

What does the command egrep file[0-9]+ ~/myfile do?

Answer 112

egrep file[0-9]+ ~/myfile matches file0, file10, and file15636.

Question 113

What does the command egrep fil* ~/myfile do?

Answer 113

egrep fil* ~/myfile matches fil, filll, and fillllllllllllllll.

Question 114

What does the command egrep fil.* ~/myfile do?

Answer 114

egrep fil.* ~/myfile matches file, fill, file102, and filings.

Question 115

What does the command egrep men|women ~/myfile do?

Answer 115

egrep men|women ~/myfile matches men or women.

Question 116

What does the command egrep Hello\? ~/myfile do?

Answer 116

egrep Hello\? ~/myfile matches Hello?.

Question 117

What does the command fgrep Midway Nimitz ~/docs/myfile do?

Answer 117

fgrep Midway Nimitz ~/docs/myfile searches myfile for lines containing Midway or Nimitz.