Linux Command Line Flashcards: Essential Commands, Flags & Workflows

このデッキのカード

1. カード 1

   質問

   Open the manual page for a command.

   回答

   Use man COMMAND, for example man ls. It opens the installed manual entry when one is available.

   Source: man-pages: man(1).

2. カード 2

   質問

   Print the current working directory.

   回答

   Use pwd. It prints the absolute path of the directory the shell is currently in.

   Source: GNU Coreutils: pwd.

3. カード 3

   質問

   Create an empty file or update a file's timestamps.

   回答

   Use touch FILE. It creates an empty file if the path does not exist; otherwise it updates the selected timestamps.

   Source: GNU Coreutils: touch.

4. カード 4

   質問

   Print a small text file to standard output.

   回答

   Use cat FILE. It copies the file's contents to standard output; use a pager such as less for long files.

   Source: GNU Coreutils: cat.

5. カード 5

   質問

   Send one command's standard output into another command.

   回答

   Use a pipe: COMMAND1 | COMMAND2. The shell connects the first command's standard output to the second command's standard input.

   Source: GNU Bash: pipelines.

6. カード 6

   質問

   Where do you see a file's permission bits in ls -l output?

   回答

   At the start of each entry, after the file-type character. A value such as -rw-r--r-- shows the type first, then user, group, and other permissions.

   Source: GNU Coreutils: long listing format.

7. カード 7

   質問

   Take a quick snapshot of processes associated with the current terminal.

   回答

   Use ps. With its default selection, it gives a one-time process listing rather than a live display.

   Source: procps-ng: ps.

8. カード 8

   質問

   Create an uncompressed tar archive from files or directories.

   回答

   Use tar -cf ARCHIVE.tar PATH.... -c creates an archive and -f names the archive file.

   Source: GNU tar: create.

9. カード 9

   質問

   Open an interactive shell on a remote machine over SSH.

   回答

   Use ssh USER@HOST. SSH connects to the remote host and can start an authenticated login session.

   Source: OpenSSH: ssh.

10. カード 10

    質問

    Display the current environment variables.

    回答

    Use env. With no command or assignments, it prints the current environment.

    Source: GNU Coreutils: env.

11. カード 11

    質問

    Ask a GNU command for its short built-in usage help.

    回答

    Try COMMAND --help. GNU command-line programs conventionally use --help for a brief usage summary; not every non-GNU command follows this convention.

    Source: GNU coding standards: --help.

12. カード 12

    質問

    List the current directory's visible entries.

    回答

    Use ls. By default, names beginning with . are omitted.

    Source: GNU Coreutils: ls.

13. カード 13

    質問

    Create a new directory.

    回答

    Use mkdir DIRECTORY. It creates the named directory when its parent already exists.

    Source: GNU Coreutils: mkdir.

14. カード 14

    質問

    Read a long text file one screen at a time.

    回答

    Use less FILE. It is a pager: move through the file interactively and press q to quit.

    Source: less: manual page.

15. カード 15

    質問

    Write standard output to a file, replacing its previous contents.

    回答

    Use COMMAND > FILE. The shell opens the file for output and truncates an existing regular file before the command writes to it.

    Source: GNU Bash: redirecting output.

16. カード 16

    質問

    What do user, group, and other mean in a file mode?

    回答

    They are three permission classes: the owning user, the owning group, and everyone else. Each class can have read, write, and execute bits.

    Source: GNU Coreutils: mode structure.

17. カード 17

    質問

    Show a broad, user-oriented snapshot of processes on a Linux system.

    回答

    Use ps aux. The BSD-style a and x options broaden the selection, while u selects a user-oriented format.

    Source: procps-ng: ps.

18. カード 18

    質問

    Extract an uncompressed tar archive into the current directory.

    回答

    Use tar -xf ARCHIVE.tar. -x extracts and -f names the archive file. Review unfamiliar archive contents before extracting them.

    Source: GNU tar: extract.

19. カード 19

    質問

    Copy a file to or from a remote machine over SSH.

    回答

    Use scp SOURCE USER@HOST:DESTINATION for an upload, or reverse the remote and local paths for a download.

    Source: OpenSSH: scp.

20. カード 20

    質問

    Print one environment variable by name.

    回答

    Use printenv NAME, for example printenv PATH. It prints that variable's value and returns a nonzero status when the name is absent.

    Source: GNU Coreutils: printenv.

21. カード 21

    質問

    Check whether Bash will treat a name as an alias, function, builtin, or executable file.

    回答

    Use type NAME. Bash reports how it would interpret the name.

    Source: GNU Bash: type.

22. カード 22

    質問

    Include hidden entries in a directory listing.

    回答

    Use ls -a. It includes names beginning with ., including . and ...

    Source: GNU Coreutils: general output formatting.

23. カード 23

    質問

    Copy a file to another path.

    回答

    Use cp SOURCE DESTINATION. If the destination names an existing file, cp can replace it, so add an interactive check when overwrites are uncertain.

    Source: GNU Coreutils: cp.

24. カード 24

    質問

    Show the first 10 lines of a text file.

    回答

    Use head FILE. Its default output is the first 10 lines; use -n NUMBER to choose another count.

    Source: GNU Coreutils: head.

25. カード 25

    質問

    Append standard output to a file without replacing its existing contents.

    回答

    Use COMMAND >> FILE. The shell opens the file in append mode, creating it if needed.

    Source: GNU Bash: appending redirected output.

26. カード 26

    質問

    What do read, write, and execute mean on a regular file?

    回答

    Read allows reading the contents, write allows modifying the contents, and execute allows the file to be run as a program when its format is executable.

    Source: GNU Coreutils: mode structure.

27. カード 27

    質問

    Find process IDs by process name.

    回答

    Use pgrep PATTERN. It searches currently running processes and prints matching process IDs.

    Source: procps-ng: pgrep.

28. カード 28

    質問

    Compress one file with gzip while keeping the original file.

    回答

    Use gzip -k FILE. GNU gzip writes FILE.gz and -k keeps the input file.

    Source: GNU gzip manual.

29. カード 29

    質問

    Fetch only a URL's response headers with curl.

    回答

    Use curl -I URL. It requests headers only; the server may respond differently than it would to a normal download.

    Source: curl: --head.

30. カード 30

    質問

    Make a shell variable available to commands started from this Bash session.

    回答

    Use export NAME=value. Bash marks the name for inclusion in the environment of subsequently executed commands.

    Source: GNU Bash: export.

31. カード 31

    質問

    Ask Bash which command it would run for a name.

    回答

    Use command -v NAME. It reports the command, builtin, function, alias, or executable Bash would use, and returns a nonzero status when none is found.

    Source: GNU Bash: command.

32. カード 32

    質問

    Show a long directory listing with modes, owners, sizes, and timestamps.

    回答

    Use ls -l. The long format adds file type and mode, link count, owner, group, size, timestamp, and name.

    Source: GNU Coreutils: long listing format.

33. カード 33

    質問

    Move or rename a file.

    回答

    Use mv SOURCE DESTINATION. Within one filesystem this commonly renames the path; it can also move it to another directory.

    Source: GNU Coreutils: mv.

34. カード 34

    質問

    Show the last 10 lines of a text file.

    回答

    Use tail FILE. Its default output is the last 10 lines; use -n NUMBER to choose another count.

    Source: GNU Coreutils: tail.

35. カード 35

    質問

    Give a command standard input from a file.

    回答

    Use COMMAND < FILE. The shell opens the file for reading on the command's standard input.

    Source: GNU Bash: redirecting input.

36. カード 36

    質問

    What do read, write, and execute mean on a directory?

    回答

    Read permits listing names, write permits changing directory entries, and execute permits traversal and access to entries by name. Creating or removing entries normally needs both write and execute permission.

    Source: GNU Coreutils: mode structure.

37. カード 37

    質問

    Watch a live, updating view of processes and resource use.

    回答

    Use top. It refreshes a process and system summary interactively; press q to quit.

    Source: procps-ng: top.

38. カード 38

    質問

    Show one path's total disk usage in a human-readable summary.

    回答

    Use du -sh PATH. -s reports one total and -h formats sizes for people.

    Source: GNU Coreutils: du.

39. カード 39

    質問

    Download a URL using its remote file name.

    回答

    Use curl -O URL. curl saves the response under the file-name part of the URL; check the target directory before downloading.

    Source: curl: --remote-name.

40. カード 40

    質問

    Search Bash command history interactively.

    回答

    Press Ctrl-R and type part of the command. Bash Readline performs a reverse incremental search through history.

    Source: GNU Bash: reverse search.

41. カード 41

    質問

    Search manual-page names and summaries by keyword.

    回答

    Use man -k KEYWORD. It searches the manual-page database's short descriptions, like apropos KEYWORD.

    Source: man-pages: man.

42. カード 42

    質問

    Show a long listing with human-readable file sizes.

    回答

    Use ls -lh. -l selects long format and -h uses human-readable size units.

    Source: GNU Coreutils: block size.

43. カード 43

    質問

    Ask before cp overwrites an existing destination file.

    回答

    Use cp -i SOURCE DESTINATION. -i prompts before replacing an existing destination.

    Source: GNU Coreutils: cp.

44. カード 44

    質問

    Keep watching new lines appended to a log file.

    回答

    Use tail -f FILE. -f keeps the command running and prints data as the file grows; stop it with Ctrl-C.

    Source: GNU Coreutils: tail.

45. カード 45

    質問

    Write only a command's error stream to a file.

    回答

    Use COMMAND 2> ERRORS.log. File descriptor 2 is standard error, so standard output stays unchanged.

    Source: GNU Bash: redirections.

46. カード 46

    質問

    Give the file owner execute permission without changing the other mode bits.

    回答

    Use chmod u+x FILE. In symbolic mode, u means owner, + adds a bit, and x means execute.

    Source: GNU Coreutils: symbolic modes.

47. カード 47

    質問

    Ask a process to terminate gracefully by PID.

    回答

    Use kill PID. By default, kill sends SIGTERM, which gives the process a chance to handle the signal and clean up.

    Source: Linux man-pages: kill.

48. カード 48

    質問

    Show free and used space for mounted filesystems in readable units.

    回答

    Use df -h. It reports filesystem space and formats sizes in powers of 1024 for easier reading.

    Source: GNU Coreutils: df.

49. カード 49

    質問

    Check whether a host responds to ICMP echo requests.

    回答

    Use ping HOST. It sends ICMP echo requests and reports replies and packet statistics; a blocked reply does not prove the host is down.

    Source: iputils: ping.

50. カード 50

    質問

    Create a short Bash name for a longer command.

    回答

    Use alias NAME='COMMAND', for example alias ll='ls -lah'. The alias lasts for the current shell unless you add it to shell startup configuration.

    Source: GNU Bash: aliases.

    

    100枚のカード

    Linux Command Line Flashcards: Essential Commands, Flags & Workflows

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51. カード 51

    質問

    Interrupt the foreground command from the terminal.

    回答

    Press Ctrl-C. The terminal normally sends SIGINT to the foreground process group.

    Source: GNU Bash: signals.

52. カード 52

    質問

    Change to another directory.

    回答

    Use cd PATH. cd is a shell builtin because it changes the shell's own working directory.

    Source: GNU Bash: cd.

53. カード 53

    質問

    Ask before mv overwrites an existing destination file.

    回答

    Use mv -i SOURCE DESTINATION. -i prompts before replacing an existing destination.

    Source: GNU Coreutils: mv.

54. カード 54

    質問

    Count the lines in a text file.

    回答

    Use wc -l FILE. -l prints the newline count.

    Source: GNU Coreutils: wc.

55. カード 55

    質問

    Send standard output and standard error to the same file.

    回答

    Use COMMAND > OUTPUT.log 2>&1. The order matters: standard error is redirected to the destination that standard output has at that point.

    Source: GNU Bash: duplicating file descriptors.

56. カード 56

    質問

    How do octal digits encode read, write, and execute permissions?

    回答

    Use 4 for read, 2 for write, and 1 for execute, then add the values for each of user, group, and other. For example, 6 means read plus write.

    Source: GNU Coreutils: numeric modes.

57. カード 57

    質問

    Force a process to stop only after graceful termination has failed.

    回答

    Use kill -KILL PID as a last resort. SIGKILL cannot be caught or ignored, so the process cannot run its normal cleanup.

    Source: Linux man-pages: signal.

58. カード 58

    質問

    List block devices in a tree without changing them.

    回答

    Use lsblk. It reads device and filesystem information and prints a tree by default.

    Source: util-linux: lsblk.

59. カード 59

    質問

    Clear the display, or recover a terminal whose state is corrupted.

    回答

    Use clear for a normal screen clear. Use reset when the terminal's modes are garbled and need reinitialization.

    Source: ncurses: clear and reset.

60. カード 60

    質問

    Move to the parent directory.

    回答

    Use cd ... In a path, .. names the parent directory.

    Source: POSIX: pathname resolution.

61. カード 61

    質問

    Remove one file without recursive deletion.

    回答

    Use rm FILE. It removes the named directory entry; this is not a trash operation, so verify the path first.

    Source: GNU Coreutils: rm.

62. カード 62

    質問

    Print lines in a file that contain a pattern.

    回答

    Use grep 'PATTERN' FILE. grep prints matching lines; quote the pattern so the shell does not reinterpret special characters.

    Source: GNU Grep manual.

63. カード 63

    質問

    Discard a command's standard output.

    回答

    Use COMMAND > /dev/null. /dev/null discards bytes written to it; standard error is still visible unless redirected separately.

    Source: Linux man-pages: null.

64. カード 64

    質問

    Change a file's owning user.

    回答

    Use chown USER FILE. Changing ownership is permission-sensitive and commonly requires elevated privileges.

    Source: GNU Coreutils: chown.

65. カード 65

    質問

    List the jobs managed by the current Bash session.

    回答

    Use jobs. It lists the shell's active jobs and their states.

    Source: GNU Bash: job-control builtins.

66. カード 66

    質問

    Show kernel and system identity details in one line.

    回答

    Use uname -a. It prints all available uname fields, including the kernel name and release, machine, and other supported details.

    Source: GNU Coreutils: uname.

67. カード 67

    質問

    Check the previous foreground pipeline's exit status in Bash.

    回答

    Read $? immediately after the command. Bash sets it to the most recently completed foreground pipeline's status; 0 conventionally means success.

    Sources: GNU Bash: special parameters; GNU Bash: exit status.

68. カード 68

    質問

    Return to the previous working directory.

    回答

    Use cd -. Bash changes to $OLDPWD and prints the resulting directory.

    Source: GNU Bash: cd.

69. カード 69

    質問

    Ask before removing a file.

    回答

    Use rm -i FILE. -i prompts before each removal.

    Source: GNU Coreutils: rm.

70. カード 70

    質問

    Search a file for a pattern without case distinctions.

    回答

    Use grep -i 'PATTERN' FILE. -i ignores case distinctions while matching.

    Source: GNU Grep: matching control.

71. カード 71

    質問

    Show command output on screen and save a copy to a file.

    回答

    Use COMMAND | tee FILE. tee copies standard input to standard output and to the named file.

    Source: GNU Coreutils: tee.

72. カード 72

    質問

    Change a file's owning group.

    回答

    Use chgrp GROUP FILE. The operation is limited by your ownership, group membership, and system privileges.

    Source: GNU Coreutils: chgrp.

73. カード 73

    質問

    Suspend the foreground job, then continue it in the background.

    回答

    Press Ctrl-Z, then run bg. The terminal normally stops the foreground job, and Bash resumes that job asynchronously.

    Source: GNU Bash: job control basics.

74. カード 74

    質問

    Show available and used memory in human-readable units.

    回答

    Use free -h. It reads memory counters exposed by the kernel and formats the values for people.

    Source: procps-ng: free.

75. カード 75

    質問

    Change to your home directory.

    回答

    Use cd ~ or simply cd in Bash. Tilde expansion turns ~ into your home directory path, and cd with no argument uses $HOME.

    Sources: GNU Bash: tilde expansion; GNU Bash: cd.

76. カード 76

    質問

    Sort text lines using the current locale's default ordering.

    回答

    Use sort FILE. It writes the sorted lines to standard output and does not change the input file unless you explicitly request an output file.

    Source: GNU Coreutils: sort.

77. カード 77

    質問

    Create a nested directory path whose parents may not exist.

    回答

    Use mkdir -p PARENT/CHILD. -p creates missing parent directories and does not fail merely because a named directory already exists.

    Source: GNU Coreutils: mkdir.

78. カード 78

    質問

    Run a second command only if the first command succeeds.

    回答

    Use COMMAND1 && COMMAND2. Bash runs the right-hand command only when the left-hand command returns status 0.

    Source: GNU Bash: AND and OR lists.

79. カード 79

    質問

    Print matching lines with their line numbers.

    回答

    Use grep -n 'PATTERN' FILE. -n prefixes each matching line with its one-based line number.

    Source: GNU Grep: output line prefix control.

80. カード 80

    質問

    Set a regular file so the owner can read and write it while everyone else can only read it.

    回答

    Use chmod 644 FILE. The digits mean owner rw-, group r--, and other r--.

    Source: GNU Coreutils: numeric modes.

81. カード 81

    質問

    Translate characters in a text stream.

    回答

    Use tr SET1 SET2, reading from standard input. For example, tr '[:lower:]' '[:upper:]' maps lowercase characters to uppercase according to the locale.

    Source: GNU Coreutils: tr.

82. カード 82

    質問

    Bring a Bash job back to the foreground.

    回答

    Use fg %JOB, or fg for the current job. Bash resumes the selected job in the foreground.

    Source: GNU Bash: job-control builtins.

83. カード 83

    質問

    How does an absolute path differ from a relative path?

    回答

    An absolute path starts with / and is resolved from the filesystem root. A relative path is resolved from the current working directory.

    Source: POSIX: pathname resolution.

84. カード 84

    質問

    Find paths below the current directory whose base name matches *.log.

    回答

    Use find . -name '*.log'. Quote the pattern so find, not the shell, performs the name match.

    Source: GNU Findutils: name test.

85. カード 85

    質問

    Remove an empty directory.

    回答

    Use rmdir DIRECTORY. It removes directories only when they are empty, which makes it safer than a recursive removal for this task.

    Source: GNU Coreutils: rmdir.

86. カード 86

    質問

    Run a fallback command only if the first command fails.

    回答

    Use COMMAND1 || COMMAND2. Bash runs the right-hand command only when the left-hand command returns a nonzero status.

    Source: GNU Bash: AND and OR lists.

87. カード 87

    質問

    Sort lines by their leading numeric value rather than lexically.

    回答

    Use sort -n FILE. Numeric sort orders lines by numeric key value instead of lexicographic text order.

    Source: GNU Coreutils: sort.

88. カード 88

    質問

    Set a directory so the owner can modify it while everyone can list and traverse it.

    回答

    Use chmod 755 DIRECTORY. The digits mean owner rwx, group r-x, and other r-x.

    Source: GNU Coreutils: numeric modes.

89. カード 89

    質問

    Print one delimited field from each input line.

    回答

    Use cut -d CHARACTER -f FIELD FILE. For example, cut -d: -f1 FILE prints the first colon-delimited field.

    Source: GNU Coreutils: cut.

90. カード 90

    質問

    Start a command as an asynchronous Bash job.

    回答

    Add &: COMMAND &. Bash starts the command in the background and returns to the prompt without waiting for it to finish.

    Source: GNU Bash: asynchronous lists.

91. カード 91

    質問

    What does ./tool say about where Bash should find tool?

    回答

    It names tool in the current directory. The ./ is an explicit relative path, so Bash does not need to search $PATH.

    Sources: POSIX: pathname resolution; GNU Bash: command search.

92. カード 92

    質問

    Search recursively through files under a directory for matching lines.

    回答

    Use grep -r 'PATTERN' DIRECTORY. -r reads files under each directory recursively and prints matching lines.

    Source: GNU Grep: file and directory selection.

93. カード 93

    質問

    Create a second hard-link name for an existing file.

    回答

    Use ln TARGET NEW_NAME. Both names refer to the same underlying file; hard links normally cannot cross filesystems or target directories.

    Source: GNU Coreutils: hard links.

94. カード 94

    質問

    Keep only one line from each adjacent run of duplicate lines.

    回答

    Use uniq. It compares adjacent lines, so sort the input first when equal lines may be separated.

    Source: GNU Coreutils: uniq.

95. カード 95

    質問

    Keep every character literal in a Bash argument, including $ and spaces.

    回答

    Wrap the text in single quotes: 'literal $HOME text'. Single quotes preserve each enclosed character literally; a single quote itself cannot appear directly inside that pair.

    Source: GNU Bash: single quotes.

96. カード 96

    質問

    What does a path beginning with / mean?

    回答

    It is an absolute path resolved from the filesystem root directory, not from the current directory.

    Source: POSIX: pathname resolution.

97. カード 97

    質問

    Find only regular files below the current directory.

    回答

    Use find . -type f. The f type test matches regular files.

    Source: GNU Findutils: type test.

98. カード 98

    質問

    Create a symbolic link that points to another path.

    回答

    Use ln -s TARGET LINK_NAME. A symbolic link stores a pathname; it can cross filesystems and can become dangling if the target path disappears.

    Source: GNU Coreutils: symbolic links.

99. カード 99

    質問

    Allow variable expansion but keep spaces inside one Bash argument.

    回答

    Use double quotes, for example "$HOME/My Files". Double quotes preserve the argument while still allowing parameter expansion and command substitution.

    Source: GNU Bash: double quotes.

100. カード 100

     質問

     Show how two text files differ.

     回答

     Use diff FILE1 FILE2. It reports the changes needed to make the files match; a status of 0 means no differences, 1 means differences, and values above 1 mean trouble.

     Source: GNU Diffutils: diff.

100枚のカード

Linux Command Line Flashcards: Essential Commands, Flags & Workflows

このデッキを無料で学習

Flashcards が開き、すぐに学習を始められます。