??通过重定向将mysql的全部man文件生成到文件mysql.txt中：
lwk@qwfys ~ $ man mysql > mysql.txt
??显示文件mysql.txt的内容
lwk@qwfys ~ $ cat mysql.txt
MYSQL(1) MySQL Database System MYSQL(1)NAMEmysql - the MySQL command-line toolSYNOPSISmysql [options] db_nameDESCRIPTIONmysql is a simple SQL shell with input line editing capabilities. It supports interactive and noninteractive use. When used interactively, query results are presented in an ASCII-table format. When used noninteractively (forexample, as a filter), the result is presented in tab-separated format. The output format can be changed using command options.If you have problems due to insufficient memory for large result sets, use the --quick option. This forces mysql to retrieve results from the server a row at a time rather than retrieving the entire result set and bufferingit in memory before displaying it. This is done by returning the result set using the mysql_use_result() C API function in the client/server library rather than mysql_store_result().NoteAlternatively, MySQL Shell offers access to the X DevAPI. For details, see Chapter 18, MySQL Shell User Guide.Using mysql is very easy. Invoke it from the prompt of your command interpreter as follows:shell> mysql db_nameOr:shell> mysql --user=user_name --password db_nameEnter password: your_passwordThen type an SQL statement, end it with ;, \g, or \G and press Enter.Typing Control+C interrupts the current statement if there is one, or cancels any partial input line otherwise.You can execute SQL statements in a script file (batch file) like this:shell> mysql db_name < script.sql > output.tabOn Unix, the mysql client logs statements executed interactively to a history file. See the section called “MYSQL LOGGING”.MYSQL OPTIONSmysql supports the following options, which can be specified on the command line or in the [mysql] and [client] groups of an option file. For information about option files used by MySQL programs, see Section 4.2.6, “UsingOption Files”.· --help, -?Display a help message and exit.· --auto-rehashEnable automatic rehashing. This option is on by default, which enables database, table, and column name completion. Use --disable-auto-rehash to disable rehashing. That causes mysql to start faster, but you must issuethe rehash command or its \# shortcut if you want to use name completion.To complete a name, enter the first part and press Tab. If the name is unambiguous, mysql completes it. Otherwise, you can press Tab again to see the possible names that begin with what you have typed so far. Completiondoes not occur if there is no default database.NoteThis feature requires a MySQL client that is compiled with the readline library. Typically, the readline library is not available on Windows.· --auto-vertical-outputCause result sets to be displayed vertically if they are too wide for the current window, and using normal tabular format otherwise. (This applies to statements terminated by ; or \G.)· --batch, -BPrint results using tab as the column separator, with each row on a new line. With this option, mysql does not use the history file.Batch mode results in nontabular output format and escaping of special characters. Escaping may be disabled by using raw mode; see the description for the --raw option.· --binary-as-hex, -bWhen this option is given, mysql displays binary data using hexadecimal notation (0xvalue). This occurs whether the overall output dislay format is tabular, vertical, HTML, or XML.This option was added in MySQL 5.7.19.· --binary-modeThis option helps when processing mysqlbinlog output that may contain BLOB values. By default, mysql translates \r\n in statement strings to \n and interprets \0 as the statement terminator. --binary-mode disables bothfeatures. It also disables all mysql commands except charset and delimiter in non-interactive mode (for input piped to mysql or loaded using the source command).· --bind-address=ip_addressOn a computer having multiple network interfaces, use this option to select which interface to use for connecting to the MySQL server.· --character-sets-dir=dir_nameThe directory where character sets are installed. See Section 10.14, “Character Set Configuration”.· --column-namesWrite column names in results.· --column-type-infoDisplay result set metadata.· --comments, -cWhether to strip or preserve comments in statements sent to the server. The default is --skip-comments (strip comments), enable with --comments (preserve comments).NoteAs of MySQL 5.7.7, the mysql client always passes optimizer hints to the server, regardless of whether this option is given. To ensure that optimizer hints are not stripped if you are using an older version of themysql client with a version of the server that understands optimizer hints, invoke mysql with the --comments option.Comment stripping is deprecated as of MySQL 5.7.20. This feature and the options to control it will be removed in a future MySQL release.· --compress, -CCompress all information sent between the client and the server if both support compression.· --connect-expired-passwordIndicate to the server that the client can handle sandbox mode if the account used to connect has an expired password. This can be useful for noninteractive invocations of mysql because normally the server disconnectsnoninteractive clients that attempt to connect using an account with an expired password. (See Section 6.3.8, “Password Expiration and Sandbox Mode”.) This option was added in MySQL 5.7.2.· --database=db_name, -D db_nameThe database to use. This is useful primarily in an option file.· --debug[=debug_options], -# [debug_options]Write a debugging log. A typical debug_options string is d:t:o,file_name. The default is d:t:o,/tmp/mysql.trace.This option is available only if MySQL was built using WITH_DEBUG. MySQL release binaries provided by Oracle are not built using this option.· --debug-checkPrint some debugging information when the program exits.· --debug-info, -TPrint debugging information and memory and CPU usage statistics when the program exits.· --default-auth=pluginA hint about the client-side authentication plugin to use. See Section 6.3.9, “Pluggable Authentication”.· --default-character-set=charset_nameUse charset_name as the default character set for the client and connection.This option can be useful if the operating system uses one character set and the mysql client by default uses another. In this case, output may be formatted incorrectly. You can usually fix such issues by using thisoption to force the client to use the system character set instead.For more information, see Section 10.4, “Connection Character Sets and Collations”, and Section 10.14, “Character Set Configuration”.· --defaults-extra-file=file_nameRead this option file after the global option file but (on Unix) before the user option file. If the file does not exist or is otherwise inaccessible, an error occurs. file_name is interpreted relative to the currentdirectory if given as a relative path name rather than a full path name.· --defaults-file=file_nameUse only the given option file. If the file does not exist or is otherwise inaccessible, an error occurs. file_name is interpreted relative to the current directory if given as a relative path name rather than a fullpath name.Exception: Even with --defaults-file, client programs read .mylogin.cnf.· --defaults-group-suffix=strRead not only the usual option groups, but also groups with the usual names and a suffix of str. For example, mysql normally reads the [client] and [mysql] groups. If the --defaults-group-suffix=_other option is given,mysql also reads the [client_other] and [mysql_other] groups.· --delimiter=strSet the statement delimiter. The default is the semicolon character (;).· --disable-named-commandsDisable named commands. Use the \* form only, or use named commands only at the beginning of a line ending with a semicolon (;). mysql starts with this option enabled by default. However, even with this option,long-format commands still work from the first line. See the section called “MYSQL COMMANDS”.· --enable-cleartext-pluginEnable the mysql_clear_password cleartext authentication plugin. (See Section 6.5.1.5, “Client-Side Cleartext Pluggable Authentication”.)· --execute=statement, -e statementExecute the statement and quit. The default output format is like that produced with --batch. See Section 4.2.4, “Using Options on the Command Line”, for some examples. With this option, mysql does not use the historyfile.· --force, -fContinue even if an SQL error occurs.· --histignoreA colon-separated list of one or more patterns specifying statements to ignore for logging purposes. These patterns are added to the default pattern list ("*IDENTIFIED*:*PASSWORD*"). The value specified for this optionaffects logging of statements written to the history file, and to syslog if the --syslog option is given. For more information, see the section called “MYSQL LOGGING”.· --host=host_name, -h host_nameConnect to the MySQL server on the given host.· --html, -HProduce HTML output.· --ignore-spaces, -iIgnore spaces after function names. The effect of this is described in the discussion for the IGNORE_SPACE SQL mode (see Section 5.1.8, “Server SQL Modes”).· --init-command=strSQL statement to execute after connecting to the server. If auto-reconnect is enabled, the statement is executed again after reconnection occurs.· --line-numbersWrite line numbers for errors. Disable this with --skip-line-numbers.· --local-infile[={0|1}]Enable or disable LOCAL capability for LOAD DATA INFILE. For mysql, this capability is disabled by default. With no value, the option enables LOCAL. The option may be given as --local-infile=0 or --local-infile=1 toexplicitly disable or enable LOCAL. Enabling local data loading also requires that the server permits it; see Section 6.1.6, “Security Issues with LOAD DATA LOCAL”· --login-path=nameRead options from the named login path in the .mylogin.cnf login path file. A “login path” is an option group containing options that specify which MySQL server to connect to and which account to authenticate as. Tocreate or modify a login path file, use the mysql_config_editor utility. See mysql_config_editor(1).· --named-commands, -GEnable named mysql commands. Long-format commands are permitted, not just short-format commands. For example, quit and \q both are recognized. Use --skip-named-commands to disable named commands. See the section called“MYSQL COMMANDS”.· --no-auto-rehash, -AThis has the same effect as --skip-auto-rehash. See the description for --auto-rehash.· --no-beep, -bDo not beep when errors occur.· --no-defaultsDo not read any option files. If program startup fails due to reading unknown options from an option file, --no-defaults can be used to prevent them from being read.The exception is that the .mylogin.cnf file, if it exists, is read in all cases. This permits passwords to be specified in a safer way than on the command line even when --no-defaults is used. (.mylogin.cnf is created bythe mysql_config_editor utility. See mysql_config_editor(1).)· --one-database, -oIgnore statements except those that occur while the default database is the one named on the command line. This option is rudimentary and should be used with care. Statement filtering is based only on USE statements.Initially, mysql executes statements in the input because specifying a database db_name on the command line is equivalent to inserting USE db_name at the beginning of the input. Then, for each USE statement encountered,mysql accepts or rejects following statements depending on whether the database named is the one on the command line. The content of the statements is immaterial.Suppose that mysql is invoked to process this set of statements:DELETE FROM db2.t2;USE db2;DROP TABLE db1.t1;CREATE TABLE db1.t1 (i INT);USE db1;INSERT INTO t1 (i) VALUES(1);CREATE TABLE db2.t1 (j INT);If the command line is mysql --force --one-database db1, mysql handles the input as follows:· The DELETE statement is executed because the default database is db1, even though the statement names a table in a different database.· The DROP TABLE and CREATE TABLE statements are not executed because the default database is not db1, even though the statements name a table in db1.· The INSERT and CREATE TABLE statements are executed because the default database is db1, even though the CREATE TABLE statement names a table in a different database.· --pager[=command]Use the given command for paging query output. If the command is omitted, the default pager is the value of your PAGER environment variable. Valid pagers are less, more, cat [> filename], and so forth. This option worksonly on Unix and only in interactive mode. To disable paging, use --skip-pager. the section called “MYSQL COMMANDS”, discusses output paging further.· --password[=password], -p[password]The password to use when connecting to the server. If you use the short option form (-p), you cannot have a space between the option and the password. If you omit the password value following the --password or -p optionon the command line, mysql prompts for one.Specifying a password on the command line should be considered insecure. See Section 6.1.2.1, “End-User Guidelines for Password Security”. You can use an option file to avoid giving the password on the command line.· --pipe, -WOn Windows, connect to the server using a named pipe. This option applies only if the server supports named-pipe connections.· --plugin-dir=dir_nameThe directory in which to look for plugins. Specify this option if the --default-auth option is used to specify an authentication plugin but mysql does not find it. See Section 6.3.9, “Pluggable Authentication”.· --port=port_num, -P port_numThe TCP/IP port number to use for the connection.· --print-defaultsPrint the program name and all options that it gets from option files.· --prompt=format_strSet the prompt to the specified format. The default is mysql>. The special sequences that the prompt can contain are described in the section called “MYSQL COMMANDS”.· --protocol={TCP|SOCKET|PIPE|MEMORY}The connection protocol to use for connecting to the server. It is useful when the other connection parameters normally would cause a protocol to be used other than the one you want. For details on the permissible values,see Section 4.2.2, “Connecting to the MySQL Server”.· --quick, -qDo not cache each query result, print each row as it is received. This may slow down the server if the output is suspended. With this option, mysql does not use the history file.· --raw, -rFor tabular output, the “boxing” around columns enables one column value to be distinguished from another. For nontabular output (such as is produced in batch mode or when the --batch or --silent option is given), specialcharacters are escaped in the output so they can be identified easily. Newline, tab, NUL, and backslash are written as \n, \t, \0, and \\. The --raw option disables this character escaping.The following example demonstrates tabular versus nontabular output and the use of raw mode to disable escaping:% mysqlmysql> SELECT CHAR(92);+----------+| CHAR(92) |+----------+| \ |+----------+% mysql -smysql> SELECT CHAR(92);CHAR(92)\\% mysql -s -rmysql> SELECT CHAR(92);CHAR(92)\· --reconnectIf the connection to the server is lost, automatically try to reconnect. A single reconnect attempt is made each time the connection is lost. To suppress reconnection behavior, use --skip-reconnect.· --safe-updates, --i-am-a-dummy, -UPermit only those UPDATE and DELETE statements that specify which rows to modify by using key values. If you have set this option in an option file, you can override it by using --safe-updates on the command line. See thesection called “MYSQL TIPS”, for more information about this option.· --secure-authDo not send passwords to the server in old (pre-4.1) format. This prevents connections except for servers that use the newer password format.As of MySQL 5.7.5, this option is deprecated and will be removed in a future MySQL release. It is always enabled and attempting to disable it (--skip-secure-auth, --secure-auth=0) produces an error. Before MySQL 5.7.5,this option is enabled by default but can be disabled.NotePasswords that use the pre-4.1 hashing method are less secure than passwords that use the native password hashing method and should be avoided. Pre-4.1 passwords are deprecated and support for them was removed inMySQL 5.7.5. For account upgrade instructions, see Section 6.5.1.3, “Migrating Away from Pre-4.1 Password Hashing and the mysql_old_password Plugin”.· --server-public-key-path=file_nameThe path name to a file containing a client-side copy of the public key required by the server for RSA key pair-based password exchange. The file must be in PEM format. This option applies to clients that authenticatewith the sha256_password authentication plugin. This option is ignored for accounts that do not authenticate with one of those plugins. It is also ignored if RSA-based password exchange is not used, as is the case whenthe client connects to the server using a secure connection.This option is available only if MySQL was built using OpenSSL.For information about the sha256_password plugin, see Section 6.5.1.4, “SHA-256 Pluggable Authentication”.· --shared-memory-base-name=nameOn Windows, the shared-memory name to use, for connections made using shared memory to a local server. The default value is MYSQL. The shared-memory name is case-sensitive.The server must be started with the --shared-memory option to enable shared-memory connections.· --show-warningsCause warnings to be shown after each statement if there are any. This option applies to interactive and batch mode.· --sigint-ignoreIgnore SIGINT signals (typically the result of typing Control+C).· --silent, -sSilent mode. Produce less output. This option can be given multiple times to produce less and less output.This option results in nontabular output format and escaping of special characters. Escaping may be disabled by using raw mode; see the description for the --raw option.· --skip-column-names, -NDo not write column names in results.· --skip-line-numbers, -LDo not write line numbers for errors. Useful when you want to compare result files that include error messages.· --socket=path, -S pathFor connections to localhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.· --ssl*Options that begin with --ssl specify whether to connect to the server using SSL and indicate where to find SSL keys and certificates. See Section 6.4.2, “Command Options for Encrypted Connections”.· --syslog, -jThis option causes mysql to send interactive statements to the system logging facility. On Unix, this is syslog; on Windows, it is the Windows Event Log. The destination where logged messages appear is system dependent.On Linux, the destination is often the /var/log/messages file.Here is a sample of output generated on Linux by using --syslog. This output is formatted for readability; each logged message actually takes a single line.Mar 7 12:39:25 myhost MysqlClient[20824]:SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23,DB_SERVER:'127.0.0.1', DB:'--', QUERY:'USE test;'Mar 7 12:39:28 myhost MysqlClient[20824]:SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23,DB_SERVER:'127.0.0.1', DB:'test', QUERY:'SHOW TABLES;'For more information, see the section called “MYSQL LOGGING”.The --syslog option was added in MySQL 5.7.1.· --table, -tDisplay output in table format. This is the default for interactive use, but can be used to produce table output in batch mode.· --tee=file_nameAppend a copy of output to the given file. This option works only in interactive mode. the section called “MYSQL COMMANDS”, discusses tee files further.· --tls-version=protocol_listThe protocols permitted by the client for encrypted connections. The value is a comma-separated list containing one or more protocol names. The protocols that can be named for this option depend on the SSL library used tocompile MySQL. For details, see Section 6.4.6, “Encrypted Connection Protocols and Ciphers”.This option was added in MySQL 5.7.10.· --unbuffered, -nFlush the buffer after each query.· --user=user_name, -u user_nameThe MySQL user name to use when connecting to the server.· --verbose, -vVerbose mode. Produce more output about what the program does. This option can be given multiple times to produce more and more output. (For example, -v -v -v produces table output format even in batch mode.)· --version, -VDisplay version information and exit.· --vertical, -EPrint query output rows vertically (one line per column value). Without this option, you can specify vertical output for individual statements by terminating them with \G.· --wait, -wIf the connection cannot be established, wait and retry instead of aborting.· --xml, -XProduce XML output.<field name="column_name">NULL</field>The output when --xml is used with mysql matches that of mysqldump --xml. See mysqldump(1), for details.The XML output also uses an XML namespace, as shown here:shell> mysql --xml -uroot -e "SHOW VARIABLES LIKE 'version%'"<?xml version="1.0"?><resultset statement="SHOW VARIABLES LIKE 'version%'" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><row><field name="Variable_name">version</field><field name="Value">5.0.40-debug</field></row><row><field name="Variable_name">version_comment</field><field name="Value">Source distribution</field></row><row><field name="Variable_name">version_compile_machine</field><field name="Value">i686</field></row><row><field name="Variable_name">version_compile_os</field><field name="Value">suse-linux-gnu</field></row></resultset>(See Bug #25946.)You can also set the following variables by using --var_name=value.· connect_timeoutThe number of seconds before connection timeout. (Default value is 0.)· max_allowed_packetThe maximum size of the buffer for client/server communication. The default is 16MB, the maximum is 1GB.· max_join_sizeThe automatic limit for rows in a join when using --safe-updates. (Default value is 1,000,000.)· net_buffer_lengthThe buffer size for TCP/IP and socket communication. (Default value is 16KB.)· select_limitThe automatic limit for SELECT statements when using --safe-updates. (Default value is 1,000.)MYSQL COMMANDSmysql sends each SQL statement that you issue to the server to be executed. There is also a set of commands that mysql itself interprets. For a list of these commands, type help or \h at the mysql> prompt:mysql> helpList of all MySQL commands:Note that all text commands must be first on line and end with ';'? (\?) Synonym for `help'.clear (\c) Clear the current input statement.connect (\r) Reconnect to the server. Optional arguments are db and host.delimiter (\d) Set statement delimiter.edit (\e) Edit command with $EDITOR.ego (\G) Send command to mysql server, display result vertically.exit (\q) Exit mysql. Same as quit.go (\g) Send command to mysql server.help (\h) Display this help.nopager (\n) Disable pager, print to stdout.notee (\t) Don't write into outfile.pager (\P) Set PAGER [to_pager]. Print the query results via PAGER.print (\p) Print current command.prompt (\R) Change your mysql prompt.quit (\q) Quit mysql.rehash (\#) Rebuild completion hash.source (\.) Execute an SQL script file. Takes a file name as an argument.status (\s) Get status information from the server.system (\!) Execute a system shell command.tee (\T) Set outfile [to_outfile]. Append everything into givenoutfile.use (\u) Use another database. Takes database name as argument.charset (\C) Switch to another charset. Might be needed for processingbinlog with multi-byte charsets.warnings (\W) Show warnings after every statement.nowarning (\w) Don't show warnings after every statement.resetconnection(\x) Clean session context.For server side help, type 'help contents'If mysql is invoked with the --binary-mode option, all mysql commands are disabled except charset and delimiter in non-interactive mode (for input piped to mysql or loaded using the source command).Each command has both a long and short form. The long form is not case-sensitive; the short form is. The long form can be followed by an optional semicolon terminator, but the short form should not.The use of short-form commands within multiple-line /* ... */ comments is not supported.· help [arg], \h [arg], \? [arg], ? [arg]Display a help message listing the available mysql commands.If you provide an argument to the help command, mysql uses it as a search string to access server-side help from the contents of the MySQL Reference Manual. For more information, see the section called “MYSQL SERVER-SIDEHELP”.· charset charset_name, \C charset_nameChange the default character set and issue a SET NAMES statement. This enables the character set to remain synchronized on the client and server if mysql is run with auto-reconnect enabled (which is not recommended),because the specified character set is used for reconnects.· clear, \cClear the current input. Use this if you change your mind about executing the statement that you are entering.· connect [db_name host_name]], \r [db_name host_name]]Reconnect to the server. The optional database name and host name arguments may be given to specify the default database or the host where the server is running. If omitted, the current values are used.· delimiter str, \d strChange the string that mysql interprets as the separator between SQL statements. The default is the semicolon character (;).The delimiter string can be specified as an unquoted or quoted argument on the delimiter command line. Quoting can be done with either single quote ('), double quote ("), or backtick (`) characters. To include a quotewithin a quoted string, either quote the string with a different quote character or escape the quote with a backslash (\) character. Backslash should be avoided outside of quoted strings because it is the escape characterfor MySQL. For an unquoted argument, the delimiter is read up to the first space or end of line. For a quoted argument, the delimiter is read up to the matching quote on the line.mysql interprets instances of the delimiter string as a statement delimiter anywhere it occurs, except within quoted strings. Be careful about defining a delimiter that might occur within other words. For example, if youdefine the delimiter as X, you will be unable to use the word INDEX in statements. mysql interprets this as INDE followed by the delimiter X.When the delimiter recognized by mysql is set to something other than the default of ;, instances of that character are sent to the server without interpretation. However, the server itself still interprets ; as astatement delimiter and processes statements accordingly. This behavior on the server side comes into play for multiple-statement execution (see Section 27.8.16, “C API Multiple Statement Execution Support”), and forparsing the body of stored procedures and functions, triggers, and events (see Section 23.1, “Defining Stored Programs”).· edit, \eEdit the current input statement. mysql checks the values of the EDITOR and VISUAL environment variables to determine which editor to use. The default editor is vi if neither variable is set.The edit command works only in Unix.· ego, \GSend the current statement to the server to be executed and display the result using vertical format.· exit, \qExit mysql.· go, \gSend the current statement to the server to be executed.· nopager, \nDisable output paging. See the description for pager.The nopager command works only in Unix.· notee, \tDisable output copying to the tee file. See the description for tee.· nowarning, \wDisable display of warnings after each statement.· pager [command], \P [command]Enable output paging. By using the --pager option when you invoke mysql, it is possible to browse or search query results in interactive mode with Unix programs such as less, more, or any other similar program. If youspecify no value for the option, mysql checks the value of the PAGER environment variable and sets the pager to that. Pager functionality works only in interactive mode.Output paging can be enabled interactively with the pager command and disabled with nopager. The command takes an optional argument; if given, the paging program is set to that. With no argument, the pager is set to thepager that was set on the command line, or stdout if no pager was specified.Output paging works only in Unix because it uses the popen() function, which does not exist on Windows. For Windows, the tee option can be used instead to save query output, although it is not as convenient as pager forbrowsing output in some situations.· print, \pPrint the current input statement without executing it.· prompt [str], \R [str]Reconfigure the mysql prompt to the given string. The special character sequences that can be used in the prompt are described later in this section.If you specify the prompt command with no argument, mysql resets the prompt to the default of mysql>.· quit, \qExit mysql.· rehash, \#Rebuild the completion hash that enables database, table, and column name completion while you are entering statements. (See the description for the --auto-rehash option.)· resetconnection, \xReset the connection to clear the session state. This command was added in MySQL 5.7.3.Resetting a connection has effects similar to mysql_change_user() or an auto-reconnect except that the connection is not closed and reopened, and re-authentication is not done. See Section 27.8.7.3, “mysql_change_user()”)and see Section 27.8.20, “C API Automatic Reconnection Control”).This example shows how resetconnection clears a value maintained in the session state:mysql> SELECT LAST_INSERT_ID(3);+-------------------+| LAST_INSERT_ID(3) |+-------------------+| 3 |+-------------------+mysql> SELECT LAST_INSERT_ID();+------------------+| LAST_INSERT_ID() |+------------------+| 3 |+------------------+mysql> resetconnection;mysql> SELECT LAST_INSERT_ID();+------------------+| LAST_INSERT_ID() |+------------------+| 0 |+------------------+· source file_name, \. file_nameRead the named file and executes the statements contained therein. On Windows, you can specify path name separators as / or \\.· status, \sProvide status information about the connection and the server you are using. If you are running in --safe-updates mode, status also prints the values for the mysql variables that affect your queries.· system command, \! commandExecute the given command using your default command interpreter.The system command works only in Unix.· tee [file_name], \T [file_name]By using the --tee option when you invoke mysql, you can log statements and their output. All the data displayed on the screen is appended into a given file. This can be very useful for debugging purposes also. mysqlflushes results to the file after each statement, just before it prints its next prompt. Tee functionality works only in interactive mode.You can enable this feature interactively with the tee command. Without a parameter, the previous file is used. The tee file can be disabled with the notee command. Executing tee again re-enables logging.· use db_name, \u db_nameUse db_name as the default database.· warnings, \WEnable display of warnings after each statement (if there are any).Here are a few tips about the pager command:· You can use it to write to a file and the results go only to the file:mysql> pager cat > /tmp/log.txtYou can also pass any options for the program that you want to use as your pager:mysql> pager less -n -i -S· In the preceding example, note the -S option. You may find it very useful for browsing wide query results. Sometimes a very wide result set is difficult to read on the screen. The -S option to less can make the result setmuch more readable because you can scroll it horizontally using the left-arrow and right-arrow keys. You can also use -S interactively within less to switch the horizontal-browse mode on and off. For more information,read the less manual page:shell> man less· The -F and -X options may be used with less to cause it to exit if output fits on one screen, which is convenient when no scrolling is necessary:mysql> pager less -n -i -S -F -X· You can specify very complex pager commands for handling query output:mysql> pager cat | tee /dr1/tmp/res.txt \| tee /dr2/tmp/res2.txt | less -n -i -SIn this example, the command would send query results to two files in two different directories on two different file systems mounted on /dr1 and /dr2, yet still display the results onscreen using less.You can also combine the tee and pager functions. Have a tee file enabled and pager set to less, and you are able to browse the results using the less program and still have everything appended into a file the same time. Thedifference between the Unix tee used with the pager command and the mysql built-in tee command is that the built-in tee works even if you do not have the Unix tee available. The built-in tee also logs everything that isprinted on the screen, whereas the Unix tee used with pager does not log quite that much. Additionally, tee file logging can be turned on and off interactively from within mysql. This is useful when you want to log somequeries to a file, but not others.The prompt command reconfigures the default mysql> prompt. The string for defining the prompt can contain the following special sequences.┌───────┬────────────────────────────────────────────────────────────────────┐│Option │ Description │├───────┼────────────────────────────────────────────────────────────────────┤│\C │ The current connection identifier (MySQL 5.7.6 and up) │├───────┼────────────────────────────────────────────────────────────────────┤│\c │ A counter that increments for each statement you issue │├───────┼────────────────────────────────────────────────────────────────────┤│\D │ The full current date │├───────┼────────────────────────────────────────────────────────────────────┤│\d │ The default database │├───────┼────────────────────────────────────────────────────────────────────┤│\h │ The server host │├───────┼────────────────────────────────────────────────────────────────────┤│\l │ The current delimiter │├───────┼────────────────────────────────────────────────────────────────────┤│\m │ Minutes of the current time │├───────┼────────────────────────────────────────────────────────────────────┤│\n │ A newline character │├───────┼────────────────────────────────────────────────────────────────────┤│\O │ The current month in three-letter format (Jan, Feb, ...) │├───────┼────────────────────────────────────────────────────────────────────┤│\o │ The current month in numeric format │├───────┼────────────────────────────────────────────────────────────────────┤│\P │ am/pm │├───────┼────────────────────────────────────────────────────────────────────┤│\p │ The current TCP/IP port or socket file │├───────┼────────────────────────────────────────────────────────────────────┤│\R │ The current time, in 24-hour military time (0–23) │├───────┼────────────────────────────────────────────────────────────────────┤│\r │ The current time, standard 12-hour time (1–12) │├───────┼────────────────────────────────────────────────────────────────────┤│\S │ Semicolon │├───────┼────────────────────────────────────────────────────────────────────┤│\s │ Seconds of the current time │├───────┼────────────────────────────────────────────────────────────────────┤│\t │ A tab character │├───────┼────────────────────────────────────────────────────────────────────┤│\U │ ││ │ Your full user_name@host_name account name │├───────┼────────────────────────────────────────────────────────────────────┤│\u │ Your user name │├───────┼────────────────────────────────────────────────────────────────────┤│\v │ The server version │├───────┼────────────────────────────────────────────────────────────────────┤│\w │ The current day of the week in three-letter format (Mon, Tue, ...) │├───────┼────────────────────────────────────────────────────────────────────┤│\Y │ The current year, four digits │├───────┼────────────────────────────────────────────────────────────────────┤│\y │ The current year, two digits │├───────┼────────────────────────────────────────────────────────────────────┤│\_ │ A space │├───────┼────────────────────────────────────────────────────────────────────┤│\ │ A space (a space follows the backslash) │├───────┼────────────────────────────────────────────────────────────────────┤│\' │ Single quote │├───────┼────────────────────────────────────────────────────────────────────┤│\" │ Double quote │├───────┼────────────────────────────────────────────────────────────────────┤│\\ │ A literal \ backslash character │├───────┼────────────────────────────────────────────────────────────────────┤│\x │ ││ │ x, for any “x” not listed above │└───────┴────────────────────────────────────────────────────────────────────┘You can set the prompt in several ways:· Use an environment variable. You can set the MYSQL_PS1 environment variable to a prompt string. For example:shell> export MYSQL_PS1="(\u@\h) [\d]> "· Use a command-line option. You can set the --prompt option on the command line to mysql. For example:shell> mysql --prompt="(\u@\h) [\d]> "(user@host) [database]>· Use an option file. You can set the prompt option in the [mysql] group of any MySQL option file, such as /etc/my.cnf or the .my.cnf file in your home directory. For example:[mysql]prompt=(\\u@\\h) [\\d]>\\_In this example, note that the backslashes are doubled. If you set the prompt using the prompt option in an option file, it is advisable to double the backslashes when using the special prompt options. There is someoverlap in the set of permissible prompt options and the set of special escape sequences that are recognized in option files. (The rules for escape sequences in option files are listed in Section 4.2.6, “Using OptionFiles”.) The overlap may cause you problems if you use single backslashes. For example, \s is interpreted as a space rather than as the current seconds value. The following example shows how to define a prompt within anoption file to include the current time in HH:MM:SS> format:[mysql]prompt="\\r:\\m:\\s> "· Set the prompt interactively. You can change your prompt interactively by using the prompt (or \R) command. For example:mysql> prompt (\u@\h) [\d]>\_PROMPT set to '(\u@\h) [\d]>\_'(user@host) [database]>(user@host) [database]> promptReturning to default PROMPT of mysql>mysql>MYSQL LOGGINGThe mysql client can do these types of logging for statements executed interactively:· On Unix, mysql writes the statements to a history file. By default, this file is named .mysql_history in your home directory. To specify a different file, set the value of the MYSQL_HISTFILE environment variable.· On all platforms, if the --syslog option is given, mysql writes the statements to the system logging facility. On Unix, this is syslog; on Windows, it is the Windows Event Log. The destination where logged messages appearis system dependent. On Linux, the destination is often the /var/log/messages file.The following discussion describes characteristics that apply to all logging types and provides information specific to each logging type. How Logging Occurs.PP For each enabled logging destination, statement logging occursas follows:· Statements are logged only when executed interactively. Statements are noninteractive, for example, when read from a file or a pipe. It is also possible to suppress statement logging by using the --batch or --executeoption.· Statements are ignored and not logged if they match any pattern in the “ignore” list. This list is described later.· mysql logs each nonignored, nonempty statement line individually.· If a nonignored statement spans multiple lines (not including the terminating delimiter), mysql concatenates the lines to form the complete statement, maps newlines to spaces, and logs the result, plus a delimiter.Consequently, an input statement that spans multiple lines can be logged twice. Consider this input:mysql> SELECT-> 'Today is'-> ,-> CURDATE()-> ;In this case, mysql logs the “SELECT”, “'Today is'”, “,”, “CURDATE()”, and “;” lines as it reads them. It also logs the complete statement, after mapping SELECT\n'Today is'\n,\nCURDATE() to SELECT 'Today is' , CURDATE(), plusa delimiter. Thus, these lines appear in logged output:SELECT'Today is',CURDATE();SELECT 'Today is' , CURDATE();mysql ignores for logging purposes statements that match any pattern in the “ignore” list. By default, the pattern list is "*IDENTIFIED*:*PASSWORD*", to ignore statements that refer to passwords. Pattern matching is not casesensitive. Within patterns, two characters are special:· ? matches any single character.· * matches any sequence of zero or more characters.To specify additional patterns, use the --histignore option or set the MYSQL_HISTIGNORE environment variable. (If both are specified, the option value takes precedence.) The value should be a colon-separated list of one ormore patterns, which are appended to the default pattern list.Patterns specified on the command line might need to be quoted or escaped to prevent your command interpreter from treating them specially. For example, to suppress logging for UPDATE and DELETE statements in addition tostatements that refer to passwords, invoke mysql like this:shell> mysql --histignore="*UPDATE*:*DELETE*"Controlling the History File.PP The .mysql_history file should be protected with a restrictive access mode because sensitive information might be written to it, such as the text of SQL statements that contain passwords. SeeSection 6.1.2.1, “End-User Guidelines for Password Security”.If you do not want to maintain a history file, first remove .mysql_history if it exists. Then use either of the following techniques to prevent it from being created again:· Set the MYSQL_HISTFILE environment variable to /dev/null. To cause this setting to take effect each time you log in, put it in one of your shell's startup files.· Create .mysql_history as a symbolic link to /dev/null; this need be done only once:shell> ln -s /dev/null $HOME/.mysql_historysyslog Logging Characteristics.PP If the --syslog option is given, mysql writes interactive statements to the system logging facility. Message logging has the following characteristics.Logging occurs at the “information” level. This corresponds to the LOG_INFO priority for syslog on Unix/Linux syslog capability and to EVENTLOG_INFORMATION_TYPE for the Windows Event Log. Consult your system documentation forconfiguration of your logging capability.Message size is limited to 1024 bytes.Messages consist of the identifier MysqlClient followed by these values:· SYSTEM_USERThe system user name (login name) or -- if the user is unknown.· MYSQL_USERThe MySQL user name (specified with the --user option) or -- if the user is unknown.· CONNECTION_ID:The client connection identifier. This is the same as the CONNECTION_ID() function value within the session.· DB_SERVERThe server host or -- if the host is unknown.· DBThe default database or -- if no database has been selected.· QUERYThe text of the logged statement.Here is a sample of output generated on Linux by using --syslog. This output is formatted for readability; each logged message actually takes a single line.Mar 7 12:39:25 myhost MysqlClient[20824]:SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23,DB_SERVER:'127.0.0.1', DB:'--', QUERY:'USE test;'Mar 7 12:39:28 myhost MysqlClient[20824]:SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23,DB_SERVER:'127.0.0.1', DB:'test', QUERY:'SHOW TABLES;'MYSQL SERVER-SIDE HELPmysql> help search_stringIf you provide an argument to the help command, mysql uses it as a search string to access server-side help from the contents of the MySQL Reference Manual. The proper operation of this command requires that the help tablesin the mysql database be initialized with help topic information (see Section 5.1.11, “Server-Side Help”).If there is no match for the search string, the search fails:mysql> help meNothing foundPlease try to run 'help contents' for a list of all accessible topicsUse help contents to see a list of the help categories:mysql> help contentsYou asked for help about help category: "Contents"For more information, type 'help <item>', where <item> is one of thefollowing categories:Account ManagementAdministrationData DefinitionData ManipulationData TypesFunctionsFunctions and Modifiers for Use with GROUP BYGeographic FeaturesLanguage StructurePluginsStorage EnginesStored RoutinesTable MaintenanceTransactionsTriggersIf the search string matches multiple items, mysql shows a list of matching topics:mysql> help logsMany help items for your request exist.To make a more specific request, please type 'help <item>',where <item> is one of the following topics:SHOWSHOW BINARY LOGSSHOW ENGINESHOW LOGSUse a topic as the search string to see the help entry for that topic:mysql> help show binary logsName: 'SHOW BINARY LOGS'Description:Syntax:SHOW BINARY LOGSSHOW MASTER LOGSLists the binary log files on the server. This statement is used aspart of the procedure described in [purge-binary-logs], that shows howto determine which logs can be purged.mysql> SHOW BINARY LOGS;+---------------+-----------+| Log_name | File_size |+---------------+-----------+| binlog.000015 | 724935 || binlog.000016 | 733481 |+---------------+-----------+The search string can contain the wildcard characters % and _. These have the same meaning as for pattern-matching operations performed with the LIKE operator. For example, HELP rep% returns a list of topics that begin withrep:mysql> HELP rep%Many help items for your request exist.To make a more specific request, please type 'help <item>',where <item> is one of the followingtopics:REPAIR TABLEREPEAT FUNCTIONREPEAT LOOPREPLACEREPLACE FUNCTIONEXECUTING SQL STATEMENTS FROM A TEXT FILEThe mysql client typically is used interactively, like this:shell> mysql db_nameHowever, it is also possible to put your SQL statements in a file and then tell mysql to read its input from that file. To do so, create a text file text_file that contains the statements you wish to execute. Then invokemysql as shown here:shell> mysql db_name < text_fileIf you place a USE db_name statement as the first statement in the file, it is unnecessary to specify the database name on the command line:shell> mysql < text_fileIf you are already running mysql, you can execute an SQL script file using the source command or \. command:mysql> source file_namemysql> \. file_nameSometimes you may want your script to display progress information to the user. For this you can insert statements like this:SELECT '<info_to_display>' AS ' ';The statement shown outputs <info_to_display>.You can also invoke mysql with the --verbose option, which causes each statement to be displayed before the result that it produces.mysql ignores Unicode byte order mark (BOM) characters at the beginning of input files. Previously, it read them and sent them to the server, resulting in a syntax error. Presence of a BOM does not cause mysql to change itsdefault character set. To do that, invoke mysql with an option such as --default-character-set=utf8.For more information about batch mode, see Section 3.5, “Using mysql in Batch Mode”.MYSQL TIPSThis section describes some techniques that can help you use mysql more effectively.Input-Line Editingmysql supports input-line editing, which enables you to modify the current input line in place or recall previous input lines. For example, the left-arrow and right-arrow keys move horizontally within the current input line,and the up-arrow and down-arrow keys move up and down through the set of previously entered lines. Backspace deletes the character before the cursor and typing new characters enters them at the cursor position. To enter theline, press Enter.On Windows, the editing key sequences are the same as supported for command editing in console windows. On Unix, the key sequences depend on the input library used to build mysql (for example, the libedit or readlinelibrary).Documentation for the libedit and readline libraries is available online. To change the set of key sequences permitted by a given input library, define key bindings in the library startup file. This is a file in your homedirectory: .editrc for libedit and .inputrc for readline.For example, in libedit, Control+W deletes everything before the current cursor position and Control+U deletes the entire line. In readline, Control+W deletes the word before the cursor and Control+U deletes everything beforethe current cursor position. If mysql was built using libedit, a user who prefers the readline behavior for these two keys can put the following lines in the .editrc file (creating the file if necessary):bind "^W" ed-delete-prev-wordbind "^U" vi-kill-line-prevTo see the current set of key bindings, temporarily put a line that says only bind at the end of .editrc. mysql will show the bindings when it starts.Unicode Support on WindowsWindows provides APIs based on UTF-16LE for reading from and writing to the console; the mysql client for Windows is able to use these APIs. The Windows installer creates an item in the MySQL menu named MySQL command lineclient - Unicode. This item invokes the mysql client with properties set to communicate through the console to the MySQL server using Unicode.To take advantage of this support manually, run mysql within a console that uses a compatible Unicode font and set the default character set to a Unicode character set that is supported for communication with the server:1. Open a console window.2. Go to the console window properties, select the font tab, and choose Lucida Console or some other compatible Unicode font. This is necessary because console windows start by default using a DOS raster font that isinadequate for Unicode.3. Execute mysql.exe with the --default-character-set=utf8 (or utf8mb4) option. This option is necessary because utf16le is not supported as a connection character set.With those changes, mysql will use the Windows APIs to communicate with the console using UTF-16LE, and communicate with the server using UTF-8. (The menu item mentioned previously sets the font and character set as justdescribed.)To avoid those steps each time you run mysql, you can create a shortcut that invokes mysql.exe. The shortcut should set the console font to Lucida Console or some other compatible Unicode font, and pass the--default-character-set=utf8 (or utf8mb4) option to mysql.exe.Alternatively, create a shortcut that only sets the console font, and set the character set in the [mysql] group of your my.ini file:[mysql]default-character-set=utf8Displaying Query Results VerticallySome query results are much more readable when displayed vertically, instead of in the usual horizontal table format. Queries can be displayed vertically by terminating the query with \G instead of a semicolon. For example,longer text values that include newlines often are much easier to read with vertical output:mysql> SELECT * FROM mails WHERE LENGTH(txt) < 300 LIMIT 300,1\G*************************** 1. row ***************************msg_nro: 3068date: 2000-03-01 23:29:50time_zone: +0200mail_from: Montyreply: monty@no.spam.commail_to: "Thimble Smith" <tim@no.spam.com>sbj: UTF-8txt: >>>>> "Thimble" == Thimble Smith writes:Thimble> Hi. I think this is a good idea. Is anyone familiarThimble> with UTF-8 or Unicode? Otherwise, I'll put this on myThimble> TODO list and see what happens.Yes, please do that.Regards,Montyfile: inbox-jani-1hash: 1904029441 row in set (0.09 sec)Using the --safe-updates OptionFor beginners, a useful startup option is --safe-updates (or --i-am-a-dummy, which has the same effect). It is helpful for cases when you might have issued a DELETE FROM tbl_name statement but forgotten the WHERE clause.Normally, such a statement deletes all rows from the table. With --safe-updates, you can delete rows only by specifying the key values that identify them. This helps prevent accidents.When you use the --safe-updates option, mysql issues the following statement when it connects to the MySQL server:SET sql_safe_updates=1, sql_select_limit=1000, max_join_size=1000000;See Section 5.1.5, “Server System Variables”.The SET statement has the following effects:· You are not permitted to execute an UPDATE or DELETE statement unless you specify a key constraint in the WHERE clause or provide a LIMIT clause (or both). For example:UPDATE tbl_name SET not_key_column=val WHERE key_column=val;UPDATE tbl_name SET not_key_column=val LIMIT 1;· The server limits all large SELECT results to 1,000 rows unless the statement includes a LIMIT clause.· The server aborts multiple-table SELECT statements that probably need to examine more than 1,000,000 row combinations.To specify limits different from 1,000 and 1,000,000, you can override the defaults by using the --select_limit and --max_join_size options:shell> mysql --safe-updates --select_limit=500 --max_join_size=10000Disabling mysql Auto-ReconnectIf the mysql client loses its connection to the server while sending a statement, it immediately and automatically tries to reconnect once to the server and send the statement again. However, even if mysql succeeds inreconnecting, your first connection has ended and all your previous session objects and settings are lost: temporary tables, the autocommit mode, and user-defined and session variables. Also, any current transaction rollsback. This behavior may be dangerous for you, as in the following example where the server was shut down and restarted between the first and second statements without you knowing it:mysql> SET @a=1;Query OK, 0 rows affected (0.05 sec)mysql> INSERT INTO t VALUES(@a);ERROR 2006: MySQL server has gone awayNo connection. Trying to reconnect...Connection id: 1Current database: testQuery OK, 1 row affected (1.30 sec)mysql> SELECT * FROM t;+------+| a |+------+| NULL |+------+1 row in set (0.05 sec)The @a user variable has been lost with the connection, and after the reconnection it is undefined. If it is important to have mysql terminate with an error if the connection has been lost, you can start the mysql client withthe --skip-reconnect option.For more information about auto-reconnect and its effect on state information when a reconnection occurs, see Section 27.8.20, “C API Automatic Reconnection Control”.COPYRIGHTCopyright ? 1997, 2018, Oracle and/or its affiliates. All rights reserved.This documentation is free software; you can redistribute it and/or modify it only under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License.This documentation is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License formore details.You should have received a copy of the GNU General Public License along with the program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or seehttp://www.gnu.org/licenses/.SEE ALSOFor more information, please refer to the MySQL Reference Manual, which may already be installed locally and which is also available online at http://dev.mysql.com/doc/.AUTHOROracle Corporation (http://dev.mysql.com/).MySQL 5.7 03/03/2018 MYSQL(1)
??至此，mysql的man文件的内容就显示完成了。