[postgres@rhel73 data]$ psql -l       ------->>>查詢默認cluster下的所有數據庫,并退出                                  List of databases   Name    |  Owner   | Encoding |   Collate   |    Ctype    |   access PRivileges   -----------+----------+----------+-------------+-------------+----------------------- postgres  | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 |  template0 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +           |          |          |             |             | postgres=CTc/postgres template1 | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | =c/postgres          +           |          |          |             |             | postgres=CTc/postgres test      | postgres | UTF8     | en_US.UTF-8 | en_US.UTF-8 | (4 rows)
[postgres@rhel73 data]$ psql -xl     ------->>>以擴展的形式查詢cluster下的所有數據庫,并退出List of databases-[ RECORD 1 ]-----+----------------------Name              | postgresOwner             | postgresEncoding          | UTF8Collate           | en_US.UTF-8Ctype             | en_US.UTF-8Access privileges | -[ RECORD 2 ]-----+----------------------Name              | template0Owner             | postgresEncoding          | UTF8Collate           | en_US.UTF-8Ctype             | en_US.UTF-8Access privileges | =c/postgres          +                  | postgres=CTc/postgres-[ RECORD 3 ]-----+----------------------Name              | template1Owner             | postgresEncoding          | UTF8Collate           | en_US.UTF-8Ctype             | en_US.UTF-8Access privileges | =c/postgres          +                  | postgres=CTc/postgres-[ RECORD 4 ]-----+----------------------Name              | testOwner             | postgresEncoding          | UTF8Collate           | en_US.UTF-8Ctype             | en_US.UTF-8Access privileges | 
[postgres@rhel73 data]$ psql --help ------------>>>>psql的幫助命令.psql is the PostgreSQL interactive terminal.Usage:  psql [OPTION]... [DBNAME [USERNAME]]General options:  -c, --command=COMMAND    run only single command (SQL or internal) and exit  -d, --dbname=DBNAME      database name to connect to (default: "postgres")  -f, --file=FILENAME      execute commands from file, then exit  -l, --list               list available databases, then exit  -v, --set=, --variable=NAME=VALUE                           set psql variable NAME to VALUE                           (e.g., -v ON_ERROR_STOP=1)  -V, --version            output version information, then exit  -X, --no-psqlrc          do not read startup file (~/.psqlrc)  -1 ("one"), --single-transaction                           execute as a single transaction (if non-interactive)  -?, --help[=options]     show this help, then exit      --help=commands      list backslash commands, then exit      --help=variables     list special variables, then exitInput and output options:  -a, --echo-all           echo all input from script  -b, --echo-errors        echo failed commands  -e, --echo-queries       echo commands sent to server  -E, --echo-hidden        display queries that internal commands generate  -L, --log-file=FILENAME  send session log to file  -n, --no-readline        disable enhanced command line editing (readline)  -o, --output=FILENAME    send query results to file (or |pipe)  -q, --quiet              run quietly (no messages, only query output)  -s, --single-step        single-step mode (confirm each query)  -S, --single-line        single-line mode (end of line terminates SQL command)Output format options:  -A, --no-align           unaligned table output mode  -F, --field-separator=STRING                           field separator for unaligned output (default: "|")  -H, --html               HTML table output mode  -P, --pset=VAR[=ARG]     set printing option VAR to ARG (see /pset command)  -R, --record-separator=STRING                           record separator for unaligned output (default: newline)  -t, --tuples-only        print rows only  -T, --table-attr=TEXT    set HTML table tag attributes (e.g., width, border)  -x, --expanded           turn on expanded table output  -z, --field-separator-zero                           set field separator for unaligned output to zero byte  -0, --record-separator-zero                           set record separator for unaligned output to zero byteConnection options:  -h, --host=HOSTNAME      database server host or socket directory (default: "local socket")  -p, --port=PORT          database server port (default: "5432")  -U, --username=USERNAME  database user name (default: "postgres")  -w, --no-passWord        never prompt for password  -W, --password           force password prompt (should happen automatically)For more information, type "/?" (for internal commands) or "/help" (for SQLcommands) from within psql, or consult the psql section in the PostgreSQLdocumentation.
Report bugs to <pgsql-bugs@postgresql.org>.[postgres@rhel73 data]$ psql -V    -------------->>>查看psql版本的命令.psql (PostgreSQL) 9.6.0[postgres@rhel73 data]$