[Linux][4_文件,打包和用户管理]

Linux文件查看

    Linux系统中使用以下命令来查看文件的内容：     cat 由第一行开始显示文件内容     tac 从最后一行开始显示，可以看出 tac 是 cat 的倒著写！     nl 显示的时候，顺道输出行号！     more 一页一页的显示文件内容     less 与 more 类似，但是比 more 更好的是，他可以往前翻页！     head 只看头几行     tail 只看尾巴几行     wc 统计文件行数

cat

man中的解释:     Concatenate FILE(s) to standard output.     With no FILE, or when FILE is -, read standard input.         -A, --show-all           equivalent to -vET         -b, --number-nonblank    number nonempty output lines, overrides -n         -e                       equivalent to -vE         -E, --show-ends          display $ at end of each line         -n, --number             number all output lines         -s, --squeeze-blank      suppress repeated empty output lines         -t                       equivalent to -vT         -T, --show-tabs          display TAB characters as ^I         -u                       (ignored)         -v, --show-nonprinting   use ^ and M- notation, except for LFD and TAB             --help     display this help and exit             --version  output version information and exit

tac

    man中的解释:     Write each FILE to standard output, last line first.     With no FILE, or when FILE is -, read standard input.     Mandatory arguments to long options are mandatory for short options too.     -b, --before             attach the separator before instead of after     -r, --regex              interpret the separator as a regular expression     -s, --separator=STRING   use STRING as the separator instead of newline         --help     display this help and exit         --version  output version information and exit

nl

    man中的解释:     Write each FILE to standard output, with line numbers added.     With no FILE, or when FILE is -, read standard input.     Mandatory arguments to long options are mandatory for short options too.     -b, --body-numbering=STYLE      use STYLE for numbering body lines     -d, --section-delimiter=CC      use CC for logical page delimiters     -f, --footer-numbering=STYLE    use STYLE for numbering footer lines     -h, --header-numbering=STYLE    use STYLE for numbering header lines     -i, --line-increment=NUMBER     line number increment at each line     -l, --join-blank-lines=NUMBER   group of NUMBER empty lines counted as one     -n, --number-format=FORMAT      insert line numbers according to FORMAT     -p, --no-renumber               do not reset line numbers for each section     -s, --number-separator=STRING   add STRING after (possible) line number     -v, --starting-line-number=NUMBER  first line number for each section     -w, --number-width=NUMBER       use NUMBER columns for line numbers         --help     display this help and exit         --version  output version information and exit

more

    man中的解释:     A file perusal filter for CRT viewing.     Options:     -d          display help instead of ringing bell     -f          count logical rather than screen lines     -l          suppress pause after form feed     -c          do not scroll, display text and clean line ends     -p          do not scroll, clean screen and display text     -s          squeeze multiple blank lines into one     -u          suppress underlining     -<number>   the number of lines per screenful     +<number>   display file beginning from line number     +/<string>  display file beginning from search string match

        --help     display this help     -V, --version  display version

less

    man中的解释:     Write each FILE to standard output, last line first.     With no FILE, or when FILE is -, read standard input.     Mandatory arguments to long options are mandatory for short options too.     -b, --before             attach the separator before instead of after     -r, --regex              interpret the separator as a regular expression     -s, --separator=STRING   use STRING as the separator instead of newline         --help     display this help and exit         --version  output version information and exit

head

    man中的解释:     Print the first 10 lines of each FILE to standard output.     With more than one FILE, precede each with a header giving the file name.     With no FILE, or when FILE is -, read standard input.     Mandatory arguments to long options are mandatory for short options too.     -c, --bytes=[-]NUM       print the first NUM bytes of each file;                                 with the leading '-', print all but the last                                 NUM bytes of each file     -n, --lines=[-]NUM       print the first NUM lines instead of the first 10;                                 with the leading '-', print all but the last                                 NUM lines of each file     -q, --quiet, --silent    never print headers giving file names     -v, --verbose            always print headers giving file names     -z, --zero-terminated    line delimiter is NUL, not newline         --help     display this help and exit         --version  output version information and exit

tail

    man中的解释:     Print the last 10 lines of each FILE to standard output.     With more than one FILE, precede each with a header giving the file name.     With no FILE, or when FILE is -, read standard input.     Mandatory arguments to long options are mandatory for short options too.     -c, --bytes=[+]NUM       output the last NUM bytes; or use -c +NUM to                                 output starting with byte NUM of each file     -f, --follow[={name|descriptor}]                             output appended data as the file grows;                                 an absent option argument means 'descriptor'     -F                       same as --follow=name --retry     -n, --lines=[+]NUM       output the last NUM lines, instead of the last 10;                                 or use -n +NUM to output starting with line NUM         --max-unchanged-stats=N                             with --follow=name, reopen a FILE which has not                                 changed size after N (default 5) iterations                                 to see if it has been unlinked or renamed                                 (this is the usual case of rotated log files);                                 with inotify, this option is rarely useful         --pid=PID            with -f, terminate after process ID, PID dies     -q, --quiet, --silent    never output headers giving file names         --retry              keep trying to open a file if it is inaccessible     -s, --sleep-interval=N   with -f, sleep for approximately N seconds                                 (default 1.0) between iterations;                                 with inotify and --pid=P, check process P at                                 least once every N seconds     -v, --verbose            always output headers giving file names     -z, --zero-terminated    line delimiter is NUL, not newline         --help     display this help and exit         --version  output version information and exit

wc

    man中的解释:     more than one FILE is specified.  A word is a non-zero-length sequence of     characters delimited by white space.

    With no FILE, or when FILE is -, read standard input.

    The options below may be used to select which counts are printed, always in     the following order: newline, word, character, byte, maximum line length.     -c, --bytes            print the byte counts     -m, --chars            print the character counts     -l, --lines            print the newline counts         --files0-from=F    read input from the files specified by                             NUL-terminated names in file F;                             If F is - then read names from standard input     -L, --max-line-length  print the maximum display width     -w, --words            print the word counts         --help     display this help and exit         --version  output version information and exit

Linux打包和压缩

tar

    man中的解释:     GNU 'tar' saves many files together into a single tape or disk archive, and can     restore individual files from the archive.

    Examples:     tar -cf archive.tar foo bar  # Create archive.tar from files foo and bar.     tar -tvf archive.tar         # List all files in archive.tar verbosely.     tar -xf archive.tar          # Extract all files from archive.tar.

    Local file name selection:

        --add-file=FILE        add given FILE to the archive (useful if its name                                 starts with a dash)     -C, --directory=DIR        change to directory DIR         --exclude=PATTERN      exclude files, given as a PATTERN         --exclude-backups      exclude backup and lock files         --exclude-caches       exclude contents of directories containing                                 CACHEDIR.TAG, except for the tag file itself         --exclude-caches-all   exclude directories containing CACHEDIR.TAG         --exclude-caches-under exclude everything under directories containing                                 CACHEDIR.TAG         --exclude-ignore=FILE  read exclude patterns for each directory from                                 FILE, if it exists         --exclude-ignore-recursive=FILE                                 read exclude patterns for each directory and its                                 subdirectories from FILE, if it exists         --exclude-tag=FILE     exclude contents of directories containing FILE,                                 except for FILE itself         --exclude-tag-all=FILE exclude directories containing FILE         --exclude-tag-under=FILE   exclude everything under directories                                 containing FILE         --exclude-vcs          exclude version control system directories         --exclude-vcs-ignores  read exclude patterns from the VCS ignore files         --no-null              disable the effect of the previous --null option         --no-recursion         avoid descending automatically in directories         --no-unquote           do not unquote input file or member names         --no-verbatim-files-from   -T treats file names starting with dash as                                 options (default)         --null                 -T reads null-terminated names; implies                                 --verbatim-files-from         --recursion            recurse into directories (default)     -T, --files-from=FILE      get names to extract or create from FILE         --unquote              unquote input file or member names (default)         --verbatim-files-from  -T reads file names verbatim (no escape or option                                 handling)     -X, --exclude-from=FILE    exclude patterns listed in FILE

    File name matching options (affect both exclude and include patterns):

        --anchored             patterns match file name start         --ignore-case          ignore case         --no-anchored          patterns match after any '/' (default for                                 exclusion)         --no-ignore-case       case sensitive matching (default)         --no-wildcards         verbatim string matching         --no-wildcards-match-slash   wildcards do not match '/'         --wildcards            use wildcards (default)         --wildcards-match-slash   wildcards match '/' (default for exclusion)

    Main operation mode:

    -A, --catenate, --concatenate   append tar files to an archive     -c, --create               create a new archive     -d, --diff, --compare      find differences between archive and file system         --delete               delete from the archive (not on mag tapes!)     -r, --append               append files to the end of an archive     -t, --list                 list the contents of an archive         --test-label           test the archive volume label and exit     -u, --update               only append files newer than copy in archive     -x, --extract, --get       extract files from an archive

    Operation modifiers:

        --check-device         check device numbers when creating incremental                                 archives (default)     -g, --listed-incremental=FILE   handle new GNU-format incremental backup     -G, --incremental          handle old GNU-format incremental backup         --hole-detection=TYPE  technique to detect holes         --ignore-failed-read   do not exit with nonzero on unreadable files         --level=NUMBER         dump level for created listed-incremental archive     -n, --seek                 archive is seekable         --no-check-device      do not check device numbers when creating                                 incremental archives         --no-seek              archive is not seekable         --occurrence[=NUMBER]  process only the NUMBERth occurrence of each file                                 in the archive; this option is valid only in                                 conjunction with one of the subcommands --delete,                                 --diff, --extract or --list and when a list of                                 files is given either on the command line or via                                 the -T option; NUMBER defaults to 1         --sparse-version=MAJOR[.MINOR]                                 set version of the sparse format to use (implies                                 --sparse)     -S, --sparse               handle sparse files efficiently

    Overwrite control:

    -k, --keep-old-files       don't replace existing files when extracting,                                 treat them as errors         --keep-directory-symlink   preserve existing symlinks to directories when                                 extracting         --keep-newer-files     don't replace existing files that are newer than                                 their archive copies         --no-overwrite-dir     preserve metadata of existing directories         --one-top-level[=DIR]  create a subdirectory to avoid having loose files                                 extracted         --overwrite            overwrite existing files when extracting         --overwrite-dir        overwrite metadata of existing directories when                                 extracting (default)         --recursive-unlink     empty hierarchies prior to extracting directory         --remove-files         remove files after adding them to the archive         --skip-old-files       don't replace existing files when extracting,                                 silently skip over them     -U, --unlink-first         remove each file prior to extracting over it     -W, --verify               attempt to verify the archive after writing it

    Select output stream:

        --ignore-command-error ignore exit codes of children         --no-ignore-command-error   treat non-zero exit codes of children as                                 error     -O, --to-stdout            extract files to standard output         --to-command=COMMAND   pipe extracted files to another program

    Handling of file attributes:

        --atime-preserve[=METHOD]   preserve access times on dumped files, either                                 by restoring the times after reading                                 (METHOD='replace'; default) or by not setting the                                 times in the first place (METHOD='system')         --clamp-mtime          only set time when the file is more recent than                                 what was given with --mtime         --delay-directory-restore   delay setting modification times and                                 permissions of extracted directories until the end                                 of extraction         --group=NAME           force NAME as group for added files         --group-map=FILE       use FILE to map file owner GIDs and names         --mode=CHANGES         force (symbolic) mode CHANGES for added files         --mtime=DATE-OR-FILE   set mtime for added files from DATE-OR-FILE     -m, --touch                don't extract file modified time         --no-delay-directory-restore                                 cancel the effect of --delay-directory-restore                                 option         --no-same-owner        extract files as yourself (default for ordinary                                 users)         --no-same-permissions  apply the user's umask when extracting permissions                                 from the archive (default for ordinary users)         --numeric-owner        always use numbers for user/group names         --owner=NAME           force NAME as owner for added files         --owner-map=FILE       use FILE to map file owner UIDs and names     -p, --preserve-permissions, --same-permissions                                 extract information about file permissions                                 (default for superuser)         --same-owner           try extracting files with the same ownership as                                 exists in the archive (default for superuser)     -s, --preserve-order, --same-order                                 member arguments are listed in the same order as                                 the files in the archive         --sort=ORDER           directory sorting order: none (default), name or                                 inode

    Handling of extended file attributes:

        --acls                 Enable the POSIX ACLs support         --no-acls              Disable the POSIX ACLs support         --no-selinux           Disable the SELinux context support         --no-xattrs            Disable extended attributes support         --selinux              Enable the SELinux context support         --xattrs               Enable extended attributes support         --xattrs-exclude=MASK  specify the exclude pattern for xattr keys         --xattrs-include=MASK  specify the include pattern for xattr keys

    Device selection and switching:

    -f, --file=ARCHIVE         use archive file or device ARCHIVE         --force-local          archive file is local even if it has a colon     -F, --info-script=NAME, --new-volume-script=NAME                                 run script at end of each tape (implies -M)     -L, --tape-length=NUMBER   change tape after writing NUMBER x 1024 bytes     -M, --multi-volume         create/list/extract multi-volume archive         --rmt-command=COMMAND  use given rmt COMMAND instead of rmt         --rsh-command=COMMAND  use remote COMMAND instead of rsh         --volno-file=FILE      use/update the volume number in FILE

    Device blocking:

    -b, --blocking-factor=BLOCKS   BLOCKS x 512 bytes per record     -B, --read-full-records    reblock as we read (for 4.2BSD pipes)     -i, --ignore-zeros         ignore zeroed blocks in archive (means EOF)         --record-size=NUMBER   NUMBER of bytes per record, multiple of 512

    Archive format selection:

    -H, --format=FORMAT        create archive of the given format

    FORMAT is one of the following:

        gnu                      GNU tar 1.13.x format         oldgnu                   GNU format as per tar <= 1.12         pax                      POSIX 1003.1-2001 (pax) format         posix                    same as pax         ustar                    POSIX 1003.1-1988 (ustar) format         v7                       old V7 tar format

        --old-archive, --portability                                 same as --format=v7         --pax-option=keyword[[:]=value][,keyword[[:]=value]]...                                 control pax keywords         --posix                same as --format=posix     -V, --label=TEXT           create archive with volume name TEXT; at                                 list/extract time, use TEXT as a globbing pattern                                 for volume name

    Compression options:

    -a, --auto-compress        use archive suffix to determine the compression                                 program     -I, --use-compress-program=PROG                                 filter through PROG (must accept -d)     -j, --bzip2                filter the archive through bzip2     -J, --xz                   filter the archive through xz         --lzip                 filter the archive through lzip         --lzma                 filter the archive through xz --format=lzma         --lzop                 filter the archive through lzop         --no-auto-compress     do not use archive suffix to determine the                                 compression program     -z, --gzip, --gunzip, --ungzip   filter the archive through gzip     -Z, --compress, --uncompress   filter the archive through compress

    Local file selection:

        --backup[=CONTROL]     backup before removal, choose version CONTROL     -h, --dereference          follow symlinks; archive and dump the files they                                 point to         --hard-dereference     follow hard links; archive and dump the files they                                 refer to     -K, --starting-file=MEMBER-NAME                                 begin at member MEMBER-NAME when reading the                                 archive         --newer-mtime=DATE     compare date and time when data changed only     -N, --newer=DATE-OR-FILE, --after-date=DATE-OR-FILE                                 only store files newer than DATE-OR-FILE         --one-file-system      stay in local file system when creating archive     -P, --absolute-names       don't strip leading '/'s from file names         --suffix=STRING        backup before removal, override usual suffix ('~'                                 unless overridden by environment variable                                 SIMPLE_BACKUP_SUFFIX)

    File name transformations:

        --strip-components=NUMBER   strip NUMBER leading components from file                                 names on extraction         --transform=EXPRESSION, --xform=EXPRESSION                                 use sed replace EXPRESSION to transform file                                 names

    Informative output:

        --checkpoint[=NUMBER]  display progress messages every NUMBERth record                                 (default 10)         --checkpoint-action=ACTION   execute ACTION on each checkpoint         --full-time            print file time to its full resolution         --index-file=FILE      send verbose output to FILE     -l, --check-links          print a message if not all links are dumped         --no-quote-chars=STRING   disable quoting for characters from STRING         --quote-chars=STRING   additionally quote characters from STRING         --quoting-style=STYLE  set name quoting style; see below for valid STYLE                                 values     -R, --block-number         show block number within archive with each message

        --show-defaults        show tar defaults         --show-omitted-dirs    when listing or extracting, list each directory                                 that does not match search criteria         --show-snapshot-field-ranges                                 show valid ranges for snapshot-file fields         --show-transformed-names, --show-stored-names                                 show file or archive names after transformation         --totals[=SIGNAL]      print total bytes after processing the archive;                                 with an argument - print total bytes when this                                 SIGNAL is delivered; Allowed signals are: SIGHUP,                                 SIGQUIT, SIGINT, SIGUSR1 and SIGUSR2; the names                                 without SIG prefix are also accepted         --utc                  print file modification times in UTC     -v, --verbose              verbosely list files processed         --warning=KEYWORD      warning control     -w, --interactive, --confirmation                                 ask for confirmation for every action

    Compatibility options:

    -o                         when creating, same as --old-archive; when                                 extracting, same as --no-same-owner

    Other options:

    -?, --help                 give this help list         --restrict             disable use of some potentially harmful options         --usage                give a short usage message         --version              print program version

gzip

    man中的解释:     Compress or uncompress FILEs (by default, compress FILES in-place).

    Mandatory arguments to long options are mandatory for short options too.

    -c, --stdout      write on standard output, keep original files unchanged     -d, --decompress  decompress     -f, --force       force overwrite of output file and compress links     -h, --help        give this help     -k, --keep        keep (don't delete) input files     -l, --list        list compressed file contents     -L, --license     display software license     -n, --no-name     do not save or restore the original name and timestamp     -N, --name        save or restore the original name and timestamp     -q, --quiet       suppress all warnings     -r, --recursive   operate recursively on directories         --rsyncable   make rsync-friendly archive     -S, --suffix=SUF  use suffix SUF on compressed files         --synchronous synchronous output (safer if system crashes, but slower)     -t, --test        test compressed file integrity     -v, --verbose     verbose mode     -V, --version     display version number     -1, --fast        compress faster     -9, --best        compress better

    With no FILE, or when FILE is -, read standard input.

bzip2

    man中的解释:     bzip2, a block-sorting file compressor.  Version 1.0.6, 6-Sept-2010.

    usage: bzip2 [flags and input files in any order]

    -h --help           print this message     -d --decompress     force decompression     -z --compress       force compression     -k --keep           keep (don't delete) input files     -f --force          overwrite existing output files     -t --test           test compressed file integrity     -c --stdout         output to standard out     -q --quiet          suppress noncritical error messages     -v --verbose        be verbose (a 2nd -v gives more)     -L --license        display software version & license     -V --version        display software version & license     -s --small          use less memory (at most 2500k)     -1 .. -9            set block size to 100k .. 900k     --fast              alias for -1     --best              alias for -9

    If invoked as `bzip2', default action is to compress.                 as `bunzip2',  default action is to decompress.                 as `bzcat', default action is to decompress to stdout.

    If no file names are given, bzip2 compresses or decompresses     from standard input to standard output.  You can combine     short flags, so `-v -4' means the same as -v4 or -4v, &c.

用户管理

用户与用户组的概念

Linux系统是一个多用户多任务的分时操作系统，任何一个要使用系统资源的用户，都必须首先向系统管理员申请一个账号，然后以这个账号的身份进入系统。

用户的账号一方面可以帮助系统管理员对使用系统的用户进行跟踪，并控制他们对系统资源的访问；另一方面也可以帮助用户组织文件，并为用户提供安全性保护

每个用户账号都拥有一个惟一的用户名和各自的口令。

用户在登录时键入正确的用户名和口令后，就能够进入系统和自己的主目录。

实现用户账号的管理，要完成的工作主要有如下几个方面：

            用户账号的添加、删除与修改。             用户口令的管理。             用户组的管理。

每个用户都有一个用户组，系统可以对一个用户组中的所有用户进行集中管理。不同Linux 系统对用户组的规定有所不同，如Linux下的用户属于与它同名的用户组,

这个用户组在创建用户时同时创建。用户组的管理涉及用户组的添加、删除和修改。组的增加、删除和修改实际上就是对/etc/group文件的更新。

常用用户命令

useradd 添加用户

    man中的解释:     Usage: useradd [options] LOGIN     useradd -D     useradd -D [options]

    Options:     -b, --base-dir BASE_DIR       base directory for the home directory of the                                     new account     -c, --comment COMMENT         GECOS field of the new account     -d, --home-dir HOME_DIR       home directory of the new account     -D, --defaults                print or change default useradd configuration     -e, --expiredate EXPIRE_DATE  expiration date of the new account     -f, --inactive INACTIVE       password inactivity period of the new account     -g, --gid GROUP               name or ID of the primary group of the new                                     account     -G, --groups GROUPS           list of supplementary groups of the new                                     account     -h, --help                    display this help message and exit     -k, --skel SKEL_DIR           use this alternative skeleton directory     -K, --key KEY=VALUE           override /etc/login.defs defaults     -l, --no-log-init             do not add the user to the lastlog and                                     faillog databases     -m, --create-home             create the user's home directory     -M, --no-create-home          do not create the user's home directory     -N, --no-user-group           do not create a group with the same name as                                     the user     -o, --non-unique              allow to create users with duplicate                                     (non-unique) UID     -p, --password PASSWORD       encrypted password of the new account     -r, --system                  create a system account     -R, --root CHROOT_DIR         directory to chroot into     -P, --prefix PREFIX_DIR       prefix directory where are located the /etc/* files     -s, --shell SHELL             login shell of the new account     -u, --uid UID                 user ID of the new account     -U, --user-group              create a group with the same name as the user     -Z, --selinux-user SEUSER     use a specific SEUSER for the SELinux user mapping

userdel 删除用户

    man中的解释:     Usage: userdel [options] LOGIN

    Options:     -f, --force                   force some actions that would fail otherwise                                     e.g. removal of user still logged in                                     or files, even if not owned by the user     -h, --help                    display this help message and exit     -r, --remove                  remove home directory and mail spool     -R, --root CHROOT_DIR         directory to chroot into     -P, --prefix PREFIX_DIR       prefix directory where are located the /etc/* files     -Z, --selinux-user            remove any SELinux user mapping for the user

    passwd 设置用户密码     man中的解释:     Usage: passwd [OPTION...] <accountName>     -k, --keep-tokens       keep non-expired authentication tokens     -d, --delete            delete the password for the named account (root only); also removes password lock if                             any     -l, --lock              lock the password for the named account (root only)     -u, --unlock            unlock the password for the named account (root only)     -e, --expire            expire the password for the named account (root only)     -f, --force             force operation     -x, --maximum=DAYS      maximum password lifetime (root only)     -n, --minimum=DAYS      minimum password lifetime (root only)     -w, --warning=DAYS      number of days warning users receives before password expiration (root only)     -i, --inactive=DAYS     number of days after password expiration when an account becomes disabled (root only)     -S, --status            report password status on the named account (root only)         --stdin             read new tokens from stdin (root only)

    Help options:     -?, --help              Show this help message         --usage             Display brief usage message

usermod 修改用户信息

    man中的解释:     Usage: usermod [options] LOGIN

    Options:     -c, --comment COMMENT         new value of the GECOS field     -d, --home HOME_DIR           new home directory for the user account     -e, --expiredate EXPIRE_DATE  set account expiration date to EXPIRE_DATE     -f, --inactive INACTIVE       set password inactive after expiration                                     to INACTIVE     -g, --gid GROUP               force use GROUP as new primary group     -G, --groups GROUPS           new list of supplementary GROUPS     -a, --append                  append the user to the supplemental GROUPS                                     mentioned by the -G option without removing                                     the user from other groups     -h, --help                    display this help message and exit     -l, --login NEW_LOGIN         new value of the login name     -L, --lock                    lock the user account     -m, --move-home               move contents of the home directory to the                                     new location (use only with -d)     -o, --non-unique              allow using duplicate (non-unique) UID     -p, --password PASSWORD       use encrypted password for the new password     -R, --root CHROOT_DIR         directory to chroot into     -P, --prefix PREFIX_DIR       prefix directory where are located the /etc/* files     -s, --shell SHELL             new login shell for the user account     -u, --uid UID                 new UID for the user account     -U, --unlock                  unlock the user account     -v, --add-subuids FIRST-LAST  add range of subordinate uids     -V, --del-subuids FIRST-LAST  remove range of subordinate uids     -w, --add-subgids FIRST-LAST  add range of subordinate gids     -W, --del-subgids FIRST-LAST  remove range of subordinate gids     -Z, --selinux-user SEUSER     new SELinux user mapping for the user account

groupadd 添加用户组

    man中的解释:     Usage: groupadd [options] GROUP

    Options:     -f, --force                   exit successfully if the group already exists,                                     and cancel -g if the GID is already used     -g, --gid GID                 use GID for the new group     -h, --help                    display this help message and exit     -K, --key KEY=VALUE           override /etc/login.defs defaults     -o, --non-unique              allow to create groups with duplicate                                     (non-unique) GID     -p, --password PASSWORD       use this encrypted password for the new group     -r, --system                  create a system account     -R, --root CHROOT_DIR         directory to chroot into     -P, --prefix PREFIX_DIR       directory prefix

    groupdel 删除用户组     man中的解释:     Usage: groupdel [options] GROUP

    Options:     -h, --help                    display this help message and exit     -R, --root CHROOT_DIR         directory to chroot into     -P, --prefix PREFIX_DIR       prefix directory where are located the /etc/* files     -f, --force                   delete group even if it is the primary group of a user

用户的家目录: /home/用户名

以管理员身份运行

su 切换当前用户身份

    man中的解释:     Usage:     su [options] [-] [<user> [<argument>...]]

    Change the effective user ID and group ID to that of <user>.     A mere - implies -l.  If <user> is not given, root is assumed.

    Options:     -m, -p, --preserve-environment  do not reset environment variables     -g, --group <group>             specify the primary group     -G, --supp-group <group>        specify a supplemental group

    -, -l, --login                  make the shell a login shell     -c, --command <command>         pass a single command to the shell with -c     --session-command <command>     pass a single command to the shell with -c                                     and do not create a new session     -f, --fast                      pass -f to the shell (for csh or tcsh)     -s, --shell <shell>             run <shell> if /etc/shells allows it     -P, --pty                       create a new pseudo-terminal

    -h, --help                      display this help     -V, --version                   display version

sudo 用root用户身份执行某条命令

    man中的解释:     sudo - execute a command as another user

    usage: sudo -h | -K | -k | -V     usage: sudo -v [-AknS] [-g group] [-h host] [-p prompt] [-u user]     usage: sudo -l [-AknS] [-g group] [-h host] [-p prompt] [-U user] [-u user] [command]     usage: sudo [-AbEHknPS] [-r role] [-t type] [-C num] [-g group] [-h host] [-p prompt] [-T timeout] [-u user]                 [VAR=value] [-i|-s] [<command>]     usage: sudo -e [-AknS] [-r role] [-t type] [-C num] [-g group] [-h host] [-p prompt] [-T timeout] [-u user] file                 ...

    Options:     -A, --askpass                 use a helper program for password prompting     -b, --background              run command in the background     -B, --bell                    ring bell when prompting     -C, --close-from=num          close all file descriptors >= num     -E, --preserve-env            preserve user environment when running command         --preserve-env=list       preserve specific environment variables     -e, --edit                    edit files instead of running a command     -g, --group=group             run command as the specified group name or ID     -H, --set-home                set HOME variable to target user's home dir     -h, --help                    display help message and exit     -h, --host=host               run command on host (if supported by plugin)     -i, --login                   run login shell as the target user; a command may also be specified     -K, --remove-timestamp        remove timestamp file completely     -k, --reset-timestamp         invalidate timestamp file     -l, --list                    list user's privileges or check a specific command; use twice for longer format     -n, --non-interactive         non-interactive mode, no prompts are used     -P, --preserve-groups         preserve group vector instead of setting to target's     -p, --prompt=prompt           use the specified password prompt     -r, --role=role               create SELinux security context with specified role     -S, --stdin                   read password from standard input     -s, --shell                   run shell as the target user; a command may also be specified     -t, --type=type               create SELinux security context with specified type     -T, --command-timeout=timeout terminate command after the specified time limit     -U, --other-user=user         in list mode, display privileges for user     -u, --user=user               run command (or edit file) as specified user name or ID     -V, --version                 display version information and exit     -v, --validate                update user's timestamp without running a command     --                            stop processing command line arguments

visudo 修改sudo命令的配置文件

    man中的解释:     visudo - safely edit the sudoers file

    usage: visudo [-chqsV] [[-f] sudoers ]

    Options:     -c, --check              check-only mode     -f, --file=sudoers       specify sudoers file location     -h, --help               display help message and exit     -q, --quiet              less verbose (quiet) syntax error messages     -s, --strict             strict syntax checking     -V, --version            display version information and exit

用户配置文件

    /etc/passwd 用户信息配置文件     /etc/shadow 用户密码信息配置文件