sed(1) sed(1)NAME sed - edits a stream of data SYNOPSIS sed [-n] -e command-line-script [file ]... sed [-n] -f scriptfile [file ]... ARGUMENTS -e command-line-script Causes the script to be taken directly from the command line (command-line-script). These options accumulate, so many scripts can be used in one invocation of the command. If there is just one -e option and no -fscriptfile options, the -e option may be omitted. Note that all shell metacharacters must be quoted when a command line script is supplied, so care must be taken when using the -e option. -f scriptfile Causes the script to be taken from file scriptfile. file Specifies the file or files that are edited, then sent to the standard output. -n Suppresses the default output: output will only be generated if explicitly asked for by certain sed commands (p, P, i, r, and the p option of the s command). DESCRIPTION sed copies the named files (standard input default) to the standard output, edited according to a script of sed commands. A script consists of editing commands, one per line, of the following form: [address[,address]] function 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 under -n) and deletes the pattern space. Some of the commands use a hold space to save all or part of the pattern space for subsequent retrieval. Replace address with either a decimal number that counts input lines cumulatively across files, a $ that addresses January 1992 1
sed(1) sed(1)the last line of input, or a context address, i.e., a /regular expression/ in the style of ed(1) modified as follows: 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 newline embedded in the pattern space. A period (.) matches any character except the terminal newline 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. Editing commands can be applied only to nonselected pattern spaces by use of the negation function (!) (see below). In the following list of functions the maximum number of permissible addresses for each function is indicated in parentheses. Replace text with one or more lines, all but the last of which end with a backslash (\) to hide the newline. Backslashes in such 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. When rfile or wfile are used in a command, they 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 Appends. Places text on the output before reading the next input line. 2 January 1992
sed(1) sed(1)(2)b label Branches to the : command bearing the label. If label is empty, branch to the end of the script. (2)c\ text Changes. Deletes the pattern space. With 0 or 1 address or at the end of a 2-address range, place text on the output. Starts the next cycle. (2)d Deletes the pattern space and starts the next cycle. (2)D Deletes the initial segment of the pattern space through the first newline, then starts the next cycle. (2)g Replaces the contents of the pattern space by the contents of the hold space. (2)G Appends the contents of the hold space to the pattern space. (2)h Replaces the contents of the hold space by the contents of the pattern space. (2)H Appends the contents of the pattern space to the hold space. (1)i\ text Inserts. Places text on the standard output. (2)l Lists the pattern space on the standard output in an unambiguous form. Non-printing characters are spelled in two-digit ASCII and long lines are folded. (2)n Copies the pattern space to the standard output. Replaces the pattern space with the next line of input. (2)N Appends the next line of input to the pattern space with an embedded newline. (The current line number changes.) (2)p Prints. Copies the pattern space to the standard output. (2)P Copies the initial segment of the pattern space through the first newline to the standard output. (1)q Quits. Branches to the end of the script. Does not start a new cycle. (1)r rfile Reads the contents of rfile. Places them on the output before reading the next input line. January 1992 3
sed(1) sed(1)(2)s /regular expression/replacement/flags Substitutes the replacement string for instances of the regular expression in the pattern space. Any character may be used instead of /. For a more complete description, see ed(1). The flags option is zero or more of: n n= 1 - 512. Substitutes for just the nth occurrence of the regular expression. g Substitutes globally. Substitute for all nonoverlapping instances of the regular expression rather than just the first one. p Prints the pattern space if a replacement was made. w wfile Writes. Appends the pattern space to wfile if a replacement was made. (2)t label Tests. Branches 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 Writes. Appends the pattern space to wfile. (2)x Exchanges the contents of the pattern and hold spaces. (2)y/string1/string2/ Transforms. Replaces all occurrences of characters in string1 with the corresponding character in string2. The lengths of string1 and string2 must be equal. (2)! function Applies the function (or group, if function is {) only to lines not selected by the address(es). (0): label Bears a label for b and t commands to branch to. This command does nothing. (1)= Places the current line number on the standard output as a line. (2){ Executes the following commands through a matching } only when the pattern space is selected. (0) Ignores an empty command. 4 January 1992
sed(1) sed(1)(0)# Treats the entire line as a comment with one exception, if this option appears as the first character on the first line of a script file. If the character after the # is an ``n'', then the default output will be suppressed, as if the -n option had been invoked. The rest of the line after #n is also ignored. It is an error for the # command to be used on any line by the first line of the file. A script file must contain at least one noncomment line. EXAMPLES The following command will process inputfile according to the sedfile script, and place the results in filea: sed -f sedfile inputfile > filea The sedfile script: 4 a\ XXXXXXXXXXXXX would insert a row of Xs after line 4. WARNINGS Operations based on a deleted line are lost. For example, if you insert text before line 4 and then delete line 4, the inserted text is lost. Reads at line 0 are actually reads before line 1, so deleting line 1 erases these reads. Writes are lost as well, although the filename is created. FILES /bin/sed Executable file SEE ALSO awk(1), ed(1), grep(1), lex(1) January 1992 5