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SED(1) General Commands Manual SED(1) NAME sed - stream editor SYNOPSIS sed [ -n ] script [ file ... ] sed [ -e script ] [ -f sfile ] [ file ... ] DESCRIPTION Sed copies the named files (standard input default) to the standard output, edited according to a command script. Script options accumu- late. -e script Script is given literally in command line. -f sfile Script is given in file sfile. -n Suppress the default output. A script consists of editing commands, usually one per line. If a com- mand ends with or the next command begins immediately thereafter. Empty commands are ignored. Commands have the form [address [, address] ] function [argument ...] [;] In normal operation sed cyclically copies a line of input into a pat- tern space (unless there is something left after a 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. An address is either a decimal number that counts input lines cumula- tively across files, a that addresses the last line of input, or a con- text address, /regular-expression/, in the style of ed(1), with the added convention that matches a newline embedded in 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. (Address is never matched.) 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 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. A text argument consists of one or more lines, all but the last of which end with to hide the newline. Backslashes in text are treated like backslashes in the replacement string of an command, and may be used to protect initial blanks and tabs against the stripping that is done on every script line. An 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 120 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 newline. 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 Literal. Place an unambiguous image of the pattern space on the standard output, using C escape sequences. Break long lines, indicating the breakpoint by a single backslash. Append \n if pattern space ends with space or newline. (2)n Copy the pattern space to the standard output. Replace the pat- tern space with the next line of input. (2)N Append the next line of input to the pattern space with an em- bedded newline. (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 newline to the standard output. (1)q Quit. Branch to the end of the script. Do not start a new cy- cle. (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 in- stead of For a fuller description see ed(1); although unlike ed , the trailing / must be supplied. Flags is zero or more of g Global. Substitute for all non-overlapping 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 replace- ment was made. (2)t label Test. Branch to the command bearing the label if any substitu- tions have been made since the most recent reading of an input line or execution of a 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)# Comment. Ignore the rest of the line. (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. EXAMPLES sed 10q file Print the first 10 lines of the file. sed '/^$/d' Delete empty lines from standard input. sed 's/UNIX/& system/g' Replace every instance of by sed 's/ *$// drop trailing blanks /^$/d drop empty lines s/ */\ replace blanks by newlines /g /^$/d' chapter* Print the files chapter1, chapter2, etc. one word to a line. nroff -ms manuscript | sed ' ${ /^$/p if last line of file is empty, print it } //N if current line is empty, append next line /^\n$/D' if two lines are empty, delete the first Delete all but one of each group of empty lines from a formatted manuscript. ls /usr/* | sed ' /^$/d delete empty lines /^[/].*:$/{ look for lines like /usr/lem: s/:$/\// replace : by / h hold directory name d don't print; get next line } G append held directory name s/\(.*\)\n\(.*\)/\2\1/' exchange file and directory List all files in user directories, as ls -d /usr/*/* would do if it didn't cause argument list overflow. SEE ALSO ed(1), gre(1), awk(1), lex(1), cut(1), split(1), sam(9.1) L. E. McMahon, `SED -- A Non-interactive Text Editor', this manual, Volume 2. BUGS If input is from a pipe, buffering may consume characters beyond a line on which a command is executed. SED(1)