SED(1) SED(1) NAME sed - stream editor SYNOPSIS sed [-n] script [file ...] sed [-n] [-e script]... [-f script_file]... [file ...] DESCRIPTION sed copies the named files (standard input default) to the standard output, edited according to a script of commands. The -e option causes the script to be take from the script option argument. The -f option causes the script to be taken from file script_file. The scripts from the -e and -f options accumulate. If there is just one -e option and no -f options, the flag -e may be omitted. The -n option suppresses the default output. sed has two operating modes. By default, sed operates compatibly with certain earlier versions of System V sed. If the environment variable _XPG is defined, and has a numeric value greater than 0, sed operates in conformance with the X/Open XPG4 specifications. In the backward compatibility mode, when -n is not specified and the "p" option to the "s" command is used, the pattern space will be output only once, no matter how many substitutions are made. Also, the format of the output of the "l" command will differ in some details from the XPG4 format. Note that the null string is a part of the solutions when _XPG numerical value > 0. i.e., sed -e 's/b*/a/' will insert "a" at the beginning of any input as "b*" would match an empty string. To substitute the first non- empty string consisting of one or more letter b's with "a", then it should be: sed -e 's/bb*/a/' A script consists of editing commands, one per line, of the following form: [ address [ , address ] ] function [ arguments ] Zero or more blank characters are accepted before the first address and before command. Each input file is a text file to be edited. The files are read in the order given. In normal operation, sed cyclically copies a line of input into a pattern space (unless there is something left after a D command), applies in sequence all commands whose addresses select that pattern space, and at the end of the script copies the pattern space to the standard output (except when -n is specified) and deletes the pattern space. Whenever the pattern space is written to standard output or a named file, sed will immediately follow it with a newline character. Some of the commands use a hold space to save all or part of the pattern space for subsequent retrieval. The hold and pattern spaces each hold at least 8192 bytes. An address is either a decimal number that counts input lines cumulatively across files, a $ that addresses the last line of input, or a context address, i.e., a /regular expression/ in the style of ed(1) modified thus: In a context address, the construction \?regular expression?, where ? is any character, is identical to /regular expression/. Note that in the context address \xabc\xdefx, the second x stands for itself, so that the regular expression is abcxdef. The escape sequence \n matches a new-line embedded in the pattern space. A period . matches any character except the terminal new-line of the pattern space. A command line with no addresses selects every pattern space. A command line with one address selects each pattern space that matches the address. A command line with two addresses selects the inclusive range from the first pattern space that matches the first address through the next pattern space that matches the second. (If the second address is a number less than or equal to the line number first selected, only one line is selected.) Thereafter the process is repeated, looking again for the first address. \< and \> are not currently supported. Editing commands can be applied only to non-selected pattern spaces by use of the negation function ! (below). In the following list of functions the maximum number of permissible addresses for each function is indicated in parentheses. The text argument consists of one or more lines, all but the last of which end with \ to hide the new-line. Backslashes in text are treated like backslashes in the replacement string of an s command, and may be used to protect initial blanks and tabs against the stripping that is done on every script line. The rfile or wfile argument must terminate the command line and must be preceded by exactly one blank. Each wfile is created before processing begins. There can be at most 10 distinct wfile arguments. (1)a\ text Append. Place text on the output before reading the next input line. (2)b label Branch to the : command bearing the label. If label is empty, branch to the end of the script. (2)c\ text Change. Delete the pattern space. With 0 or 1 address or at the end of a 2-address range, place text on the output. Start the next cycle. (2)d Delete the pattern space. Start the next cycle. (2)D Delete the initial segment of the pattern space through the first new-line. Start the next cycle. (2)g Replace the contents of the pattern space by the contents of the hold space. (2)G Append the contents of the hold space to the pattern space. (2)h Replace the contents of the hold space by the contents of the pattern space. (2)H Append the contents of the pattern space to the hold space. (1)i\ text Insert. Place text on the standard output. (2)l List the pattern space on the standard output in an unambiguous form. Non-printable characters are displayed in octal notation and long lines are folded. (2)n Copy the pattern space to the standard output. Replace the pattern space with the next line of input. (2)N Append the next line of input to the pattern space with an embedded new-line. (The current line number changes.) (2)p Print. Copy the pattern space to the standard output. (2)P Copy the initial segment of the pattern space through the first new-line to the standard output. (1)q Quit. Branch to the end of the script. Do not start a new cycle. (2)r rfile Read the contents of rfile. Place them on the output before reading the next input line. (2)s/regular expression/replacement/flags Substitute the replacement string for instances of the regular expression in the pattern space. Any character may be used instead of /. For a fuller description see ed(1). Flags is zero or more of: n n= 1 - 512. Substitute for just the n th occurrence of the regular expression. g Global. Substitute for all nonoverlapping instances of the regular expression rather than just the first one. p Print the pattern space if a replacement was made. w wfile Write. Append the pattern space to wfile if a replacement was made. (2)t label Test. Branch to the : command bearing the label if any substitutions have been made since the most recent reading of an input line or execution of a t. If label is empty, branch to the end of the script. (2)w wfile Write. Append the pattern space to wfile. (2)x Exchange the contents of the pattern and hold spaces. (2)y/string1/string2/ Transform. Replace all occurrences of characters in string1 with the corresponding character in string2. The lengths of string1 and string2 must be equal. (2)! function Don't. Apply the function (or group, if function is {) only to lines not selected by the address(es). (0): label This command does nothing; it bears a label for b and t commands to branch to. (1)= Place the current line number on the standard output as a line. (2){ Execute the following commands through a matching } only when the pattern space is selected. (0) An empty command is ignored. (0)# If a # appears as the first character on a line of a script file, then that entire line is treated as a comment, with one exception. If the character after the # is an 'n', then the default output will be suppressed. The rest of the line after #n is also ignored. A script file must contain at least one non-comment line. PERFORMANCE The regular expression routines used by sed comply with POSIX standards, including full backtracking. This can substantially reduce performance when using regular expressions with multiple wildcards on large amounts of data. The alternate command osed can be many times faster evaluating multiple wildcards, but does not comply with POSIX. The sed command automatically invokes /usr/bin/osed if the environment variable FAST_REGEX_CMDS is set, unless POSIXLY_CORRECT is also set. Note that the osed command may not produce proper results if the input files contain multibyte data. SEE ALSO awk(1), ed(1), grep(1), osed(1), regcomp(5). Page 4