![]() ![]() The first-through-last lines in the buffer. The nth next line, where n is a non-negative number. ![]() This option is equivalent to +1 and may be repeated with cumulative effect. The nth previous line, where n is a non-negative number. This option is equivalent to -1 and may be repeated with cumulative effect. The nth line in the buffer where n is a number in the range. The current line (address) in the buffer. The following address symbols are recognized. In a semicolon-delimited range, the first address is used to set the current address, and the second address is interpreted relative to the first. If only one address is given in a range, then the second address is set to the given address.Įach address in a comma- delimited range is interpreted relative to the current address. The value of the first address in a range cannot exceed the value of the second. Address rangesĪn address range is two addresses separated either by a comma (" ,") or semicolon (" "). This address means "before the first line," and can be used in any command. One exception to the rule that addresses represent line numbers is the special address 0 (zero). Addresses are read from left to right, and their values are computed relative to the current address. The offset may include any combination of digits, operators (for instance, " +" and " -") and whitespace. Referring to line addressesĪ reference to a line address is constructed from one of the bases in the list below, optionally followed by a numeric offset. Think of the address as a place marker to the last line in the file where ed has done something, and, unless told otherwise, the line where it operates next. In general, at any given time, the current address is set to the last line affected by a command. When a file is first read, the current address is set to the last line of the file. ed maintains a current address that is supplied to commands as the default address if none other is specified. Line addressesĪn address represents the number of a line in the buffer. If fewer addresses are given than the command accepts, then default addresses are supplied. The address(es) indicate the line or range of lines to be affected by the command. In general, ed commands consist of zero or more line addresses, followed by a single character command and possibly additional parameters. It is possible to modify only a portion of a line by specific replacement, as in the example above although even then, the ' s' command is applied to whole lines at a time. For example, the ' d' command deletes lines the ' m' command moves lines, etc. ") on a line.Īn important thing to remember is that all ed commands operate on whole lines or ranges of lines. Input mode is exited by entering a single period (". Lines consist of text up to and including a newline character. In this mode, no commands are available instead, the standard input is written directly to the editor buffer. This mode is the primary means of adding text to a file. When an input command, such as ' a' (append), ' i' (insert), or ' c' (change) is given, ed enters input mode. Which replaces all occurrences of the string old with the string new. A typical command might look like: ,s/old/new/g In this mode, commands are read from the standard input and executed to manipulate the contents of the editor buffer. When first invoked, ed is in command mode. Upon quitting ed, any changes not explicitly saved with a ' w' command are lost.Įditing is performed in two distinct modes: command and input. Changes are made to this copy and not directly to file itself. If ed is invoked with a file name argument, then a copy of file is read into the editor's buffer. It is used to create, display, modify and otherwise manipulate text files. This option can be useful if ed is set to be the editor for crontab, for instance.Įd usually waits for user input at a blank line this option uses the string STRING as the prompt instead.Įd is a line-oriented text editor with a minimal interface. Syntax ed red Options -h, -helpĮxit with a status of zero (normal termination) even if a command fails. It was introduced in 1969, approximately 50 years ago, as one of the original components of Unix. Ed is one of the oldest editing programs around. ![]()
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