elements of power system analysis

Production environment configuration:Operating system: CentOS 6.61. The problem arises:"SERADD:CANNOTOPEN/ETC/PASSWD" appears when you add an account using the Useradd command[[Email protected] ~] #useradd-D/home/wwwroot/ftupuser-g ftp-s/sbin/nologin Ftpuseruseradd:cannotopen/etc/passwd2. reasons for the resulting:a) After adding the "I" hidden property, the file cannot be changed. [[Email protected] ~] #chattr +i/etc/passwd[[Email protected] ~] #c

redirect error is generated. If Word expands to "-", the file descriptor n is closed. If n is not specified, standard input (file descriptor 0) is used.[N]>wordThis operator is also used to copy output file descriptors. If n is not specified, standard output (file descriptor 1) is used. If a number in Word does not specify a file descriptor to be used for output, a redirect error is generated. In special cases, if n is skipped, and word is not expanded to one or more numbers, standard output an

Notification, and Raw Notification. WP7 's main screen is full of applications more like a block of square tiles, as the name suggests tile notification is what appears in these "tiles" on the notice, such as the main screen on the weather on the app on the temperature changes appear when the notice. By changing the three elements on the tile (title, Backgroud and hint) to achieve the purpose of the reminder, compared with iOS badge notification, in