history_offset = history_length; free (temp) ; return (char *)NULL; \ } while (0)/* If there is no search string, try to use the previous search string, if one exists. If not, fail immediately. */if(*temp =='\0'&& substring_okay) {if(search_string) {free(temp); temp = s...
So we want to prepend sudo to the previous command. Of course, we can press Ctrl-p to recall the last command, move the cursor to the right position, and type sudo. Well, “sudo” is short, and moving the cursor (pressing Ctrl-a) to the very beginning isn’t hard to do. However...
首先,Shell 是一个程序,提供一个与用户对话的环境。这个环境只有一个命令提示符,让用户从键盘输入命令,所以又称为命令行环境(commandline,简写为 CLI)。Shell 接收到用户输入的命令,将命令送入操作系统执行,并将结果返回给用户。本书中,除非特别指明,Shell 指的就是命令行环境。 其次,Shell 是一个命令解释器,解释...
Subsequently, expands to the last argument to the previous command, after expansion. Also set to the full pathname used to invoke each command exe cuted and placed in the environment exported to that command. When checking mail, this parameter holds the name of the mail file currently being ch...
Commands for Manipulating the History 操縱歷史行 accept-line (Newline, Return) 接受這一行,不管游標在什麼位置。如果行非空,將根據變數 HISTCONTROL 的狀態加入到歷史列表中。如果行 是修改過的歷史行,將恢復該歷史行到初始狀態。 previous-history (C-p) 從歷史列表中取得前一個命令,從列表中向後移動。
Commands for Manipulating the History 操縱歷史行 accept-line (Newline, Return) 接受這一行,不管光標在什麼位置。如果行非空,將根據變量 HISTCONTROL 的狀態加入到歷史列表中。如果行 是修改過的歷史行,將恢復該歷史行到初始狀態。 previous-history (C-p) 從歷史列表中取得前一個命令,從列表中向後移動。
for each new session. If you customize PROMPT_COMMAND # be sure to include the previous value....
The return status of a pipeline is the exit status of the last command, unless the pipefail option is enabled. If pipefail is enabled, the pipeline's return status is the value of the last (rightmost) command to exit with a non- zero status, or zero if all commands exit successfully....
for each new session. If you customize PROMPT_COMMAND # be sure to include the previous value....
Syntax: return [n] where n is a number. If n is not supplied, then it will return the exit code of the last command run. Though, the possible value range for the return builtin is limited to the least significant 8 bits which are 0 to 255. Any number above 255 will just return ...