sed(1) sed(1)NAME sed - stream editor SYNOPSIS sed [-n] -e command-line-script [file...] sed [-n] -f sfile [file...] DESCRIPTION sed copies the named files (standard input default) to the standard output, edited according to a script of sed com- mands. The -f flag option causes the script to be taken from file sfile. The -e flag option causes the script to be taken directly from the command line. These flag options accumulate, so many scripts can be used in one invocation of the command. If there is just one -e flag option and no -f flag options, the -e flag 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 flag option. The -n flag option 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 com- mand). 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. 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 ex- pression/ 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 con- text address \xabc\xdefx, the second x stands for itself, so that the regular expression is abcxdef. April, 1990 1
sed(1) sed(1)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. The text argument used in some of the commands consists of 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. An rfile or wfile argument in a command 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, 2 April, 1990
sed(1) sed(1)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 cy- cle. (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-printing characters are spelled in two-digit ASCII 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 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 out- put. (1)q Quit. Branch to the end of the script. Do not start a new cycle. (1)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 April, 1990 3
sed(1) sed(1)of the regular expression in the pattern space. Any character may be used instead of /. For a more complete description, see ed(1). flags is zero or more of: n n= 1 - 512. Substitute for just the nth occurrence of the regular expression. g Global. Substitute for all nono- verlapping instances of the regular expression rather than just the first one. p Print the pattern space if a re- placement 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 execu- tion 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 charac- ters in string1 with the corresponding character in string2. The lengths of string1 and string2 must be equal. (2)! function 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 match- ing } only when the pattern space is selected. (0) An empty command is ignored. 4 April, 1990
sed(1) sed(1)(0)# If a # appears as the first character on the first line of a script file, then that entire line is treated as a comment, with one excep- tion. If the character after the # is an ``n'', then the default output will be suppressed, as if the -n flag 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 byt 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. FILES /bin/sed SEE ALSO awk(1), ed(1), grep(1), lex(1). 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. April, 1990 5