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This is Info file sed.info, produced by Makeinfo version 1.68 from the input file sed.texi. START-INFO-DIR-ENTRY * sed: (sed). Stream EDitor. END-INFO-DIR-ENTRY This file documents SED, a stream editor. Published by the Free Software Foundation, 59 Temple Place - Suite 330 Boston, MA 02111-1307, USA Copyright (C) 1998 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the Foundation. File: sed.info, Node: Top, Next: Introduction, Prev: (dir), Up: (dir) This document was produced for version 3.02 of GNU SED. * Menu: * Introduction:: Introduction * Invoking SED:: Invocation * sed Programs:: SED programs * Examples:: Some sample scripts * Limitations:: About the (non-)limitations on line length * Other Resources:: Other resources for learning about SED * Reporting Bugs:: Reporting bugs * Concept Index:: A menu with all the topics in this manual. * Command and Option Index:: A menu with all SED commands and command-line options. File: sed.info, Node: Introduction, Next: Invoking SED, Prev: Top, Up: Top Introduction ************ SED is a stream editor. A stream editor is used to perform basic text transformations on an input stream (a file or input from a pipeline). While in some ways similar to an editor which permits scripted edits (such as ED), SED works by making only one pass over the input(s), and is consequently more efficient. But it is SED's ability to filter text in a pipeline which particularly distinguishes it from other types of editors. File: sed.info, Node: Invoking SED, Next: sed Programs, Prev: Introduction, Up: Top Invocation ********** SED may be invoked with the following command-line options: `-V' `--version' Print out the version of SED that is being run and a copyright notice, then exit. `-h' `--help' Print a usage message briefly summarizing these command-line options and the bug-reporting address, then exit. `-n' `--quiet' `--silent' By default, SED will print out the pattern space at then end of each cycle through the script. These options disable this automatic printing, and SED will only produce output when explicitly told to via the `p' command. `-e SCRIPT' `--expression=SCRIPT' Add the commands in SCRIPT to the set of commands to be run while processing the input. `-f SCRIPT-FILE' `--file=SCRIPT-FILE' Add the commands contained in the file SCRIPT-FILE to the set of commands to be run while processing the input. If no `-e', `-f', `--expression', or `--file' options are given on the command-line, then the first non-option argument on the command line is taken to be the SCRIPT to be executed. If any command-line parameters remain after processing the above, these parameters are interpreted as the names of input files to be processed. A file name of `-' refers to the standard input stream. The standard input will processed if no file names are specified. File: sed.info, Node: sed Programs, Next: Examples, Prev: Invoking SED, Up: Top SED Programs ************ A SED program consists of one or more SED commands, passed in by one or more of the `-e', `-f', `--expression', and `--file' options, or the first non-option argument if zero of these options are used. This document will refer to "the" SED script; this will be understood to mean the in-order catenation of all of the SCRIPTs and SCRIPT-FILEs passed in. Each SED command consists of an optional address or address range, followed by a one-character command name and any additional command-specific code. * Menu: * Addresses:: Selecting lines with SED * Regular Expressions:: Overview of regular expression syntax * Data Spaces:: Where SED buffers data * Common Commands:: Often used commands * Other Commands:: Less frequently used commands * Programming Commands:: Commands for die-hard SED programmers File: sed.info, Node: Addresses, Next: Regular Expressions, Prev: sed Programs, Up: sed Programs Selecting lines with SED ======================== Addresses in a SED script can be in any of the following forms: `NUMBER' Specifying a line number will match only that line in the input. (Note that SED counts lines continuously across all input files.) `FIRST~STEP' This GNU extension matches every STEPth line starting with line FIRST. In particular, lines will be selected when there exists a non-negative N such that the current line-number equals FIRST + (N * STEP). Thus, to select the odd-numbered lines, one would use `1~2'; to pick every third line starting with the second, `2~3' would be used; to pick every fifth line starting with the tenth, use `10~5'; and `50~0' is just an obscure way of saying `50'. `$' This address matches the last line of the last file of input. `/REGEXP/' This will select any line which matches the regular expression REGEXP. If REGEXP itself includes any `/' characters, each must be escaped by a backslash (`\'). `\%REGEXP%' (The `%' may be replaced by any other single character.) This also matches the regular expression REGEXP, but allows one to use a different delimiter than `/'. This is particularly useful if the REGEXP itself contains a lot of `/'s, since it avoids the tedious escaping of every `/'. If REGEXP itself includes any delimiter characters, each must be escaped by a backslash (`\'). `/REGEXP/I' `\%REGEXP%I' The `I' modifier to regular-expression matching is a GNU extension which causes the REGEXP to be matched in a case-insensitive manner. If no addresses are given, then all lines are matched; if one address is given, then only lines matching that address are matched. An address range can be specified by specifying two addresses separated by a comma (`,'). An address range matches lines starting from where the first address matches, and continues until the second address matches (inclusively). If the second address is a REGEXP, then checking for the ending match will start with the line *following* the line which matched the first address. If the second address is a NUMBER less than (or equal to) the line matching the first address, then only the one line is matched. Appending the `!' character to the end of an address specification will negate the sense of the match. That is, if the `!' character follows an address range, then only lines which do *not* match the address range will be selected. This also works for singleton addresses, and, perhaps perversely, for the null address. File: sed.info, Node: Regular Expressions, Next: Data Spaces, Prev: Addresses, Up: sed Programs Overview of regular expression syntax ===================================== [[I may add a brief overview of regular expressions at a later date; for now see any of the various other documentations for regular expressions, such as the AWK info page.]] File: sed.info, Node: Data Spaces, Next: Common Commands, Prev: Regular Expressions, Up: sed Programs Where SED buffers data ====================== SED maintains two data buffers: the active *pattern* space, and the auxiliary *hold* space. In "normal" operation, SED reads in one line from the input stream and places it in the pattern space. This pattern space is where text manipulations occur. The hold space is initially empty, but there are commands for moving data between the pattern and hold spaces. File: sed.info, Node: Common Commands, Next: Other Commands, Prev: Data Spaces, Up: sed Programs Often used commands =================== If you use SED at all, you will quite likely want to know these commands. `#' [No addresses allowed.] The `#' "command" begins a comment; the comment continues until the next newline. If you are concerned about portability, be aware that some implementations of SED (which are not POSIX.2 conformant) may only support a single one-line comment, and then only when the very first character of the script is a `#'. Warning: if the first two characters of the SED script are `#n', then the `-n' (no-autoprint) option is forced. If you want to put a comment in the first line of your script and that comment begins with the letter `n' and you do not want this behavior, then be sure to either use a capital `N', or place at least one space before the `n'. `s/REGEXP/REPLACEMENT/FLAGS' (The `/' characters may be uniformly replaced by any other single character within any given `s' command.) The `/' character (or whatever other character is used in its stead) can appear in the REGEXP or REPLACEMENT only if it is preceded by a `\' character. Also newlines may appear in the REGEXP using the two character sequence `\n'. The `s' command attempts to match the pattern space against the supplied REGEXP. If the match is successful, then that portion of the pattern space which was matched is replaced with REPLACEMENT. The REPLACEMENT can contain `\N' (N being a number from 1 to 9, inclusive) references, which refer to the portion of the match which is contained between the Nth `$' and its matching `$'. Also, the REPLACEMENT can contain unescaped `&' characters which will reference the whole matched portion of the pattern space. To include a literal `\', `&', or newline in the final replacement, be sure to precede the desired `\', `&', or newline in the REPLACEMENT with a `\'. The `s' command can be followed with zero or more of the following FLAGS: `g' Apply the replacement to *all* matches to the REGEXP, not just the first. `p' If the substitution was made, then print the new pattern space. `NUMBER' Only replace the NUMBERth match of the REGEXP. `w FILE-NAME' If the substitution was made, then write out the result to the named file. `I' (This is a GNU extension.) Match REGEXP in a case-insensitive manner. `q' [At most one address allowed.] Exit SED without processing any more commands or input. Note that the current pattern space is printed if auto-print is not disabled. `d' Delete the pattern space; immediately start next cycle. `p' Print out the pattern space (to the standard output). This command is usually only used in conjunction with the `-n' command-line option. Note: some implementations of SED, such as this one, will double-print lines when auto-print is not disabled and the `p' command is given. Other implementations will only print the line once. Both ways conform with the POSIX.2 standard, and so neither way can be considered to be in error. Portable SED scripts should thus avoid relying on either behavior; either use the `-n' option and explicitly print what you want, or avoid use of the `p' command (and also the `p' flag to the `s' command). `n' If auto-print is not disabled, print the pattern space, then, regardless, replace the pattern space with the next line of input. If there is no more input then SED exits without processing any more commands. `{ COMMANDS }' A group of commands may be enclosed between `{' and `}' characters. (The `}' must appear in a zero-address command context.) This is particularly useful when you want a group of commands to be triggered by a single address (or address-range) match. File: sed.info, Node: Other Commands, Next: Programming Commands, Prev: Common Commands, Up: sed Programs Less frequently used commands ============================= Though perhaps less frequently used than those in the previous section, some very small yet useful SED scripts can be built with these commands. `y/SOURCE-CHARS/DEST-CHARS/' (The `/' characters may be uniformly replaced by any other single character within any given `y' command.) Transliterate any characters in the pattern space which match any of the SOURCE-CHARS with the corresponding character in DEST-CHARS. Instances of the `/' (or whatever other character is used in its stead), `\', or newlines can appear in the SOURCE-CHARS or DEST-CHARS lists, provide that each instance is escaped by a `\'. The SOURCE-CHARS and DEST-CHARS lists *must* contain the same number of characters (after de-escaping). `a\' `TEXT' [At most one address allowed.] Queue the lines of text which follow this command (each but the last ending with a `\', which will be removed from the output) to be output at the end of the current cycle, or when the next input line is read. `i\' `TEXT' [At most one address allowed.] Immediately output the lines of text which follow this command (each but the last ending with a `\', which will be removed from the output). `c\' `TEXT' Delete the lines matching the address or address-range, and output the lines of text which follow this command (each but the last ending with a `\', which will be removed from the output) in place of the last line (or in place of each line, if no addresses were specified). A new cycle is started after this command is done, since the pattern space will have been deleted. `=' [At most one address allowed.] Print out the current input line number (with a trailing newline). `l' Print the pattern space in an unambiguous form: non-printable characters (and the `\' character) are printed in C-style escaped form; long lines are split, with a trailing `\' character to indicate the split; the end of each line is marked with a `$'. `r FILENAME' [At most one address allowed.] Queue the contents of FILENAME to be read and inserted into the output stream at the end of the current cycle, or when the next input line is read. Note that if FILENAME cannot be read, it is treated as if it were an empty file, without any error indication. `w FILENAME' Write the pattern space to FILENAME. The FILENAME will be created (or truncated) before the first input line is read; all `w' commands (including instances of `w' flag on successful `s' commands) which refer to the same FILENAME are output through the same FILE stream. `D' Delete text in the pattern space up to the first newline. If any text is left, restart cycle with the resultant pattern space (without reading a new line of input), otherwise start a normal new cycle. `N' Add a newline to the pattern space, then append the next line of input to the pattern space. If there is no more input then SED exits without processing any more commands. `P' Print out the portion of the pattern space up to the first newline. `h' Replace the contents of the hold space with the contents of the pattern space. `H' Append a newline to the contents of the hold space, and then append the contents of the pattern space to that of the hold space. `g' Replace the contents of the pattern space with the contents of the hold space. `G' Append a newline to the contents of the pattern space, and then append the contents of the hold space to that of the pattern space. `x' Exchange the contents of the hold and pattern spaces. File: sed.info, Node: Programming Commands, Prev: Other Commands, Up: sed Programs Commands for die-hard SED programmers ===================================== In most cases, use of these commands indicates that you are probably better off programming in something like PERL. But occasionally one is committed to sticking with SED, and these commands can enable one to write quite convoluted scripts. `: LABEL' [No addresses allowed.] Specify the location of LABEL for the `b' and `t' commands. In all other respects, a no-op. `b LABEL' Unconditionally branch to LABEL. The LABEL may be omitted, in which case the next cycle is started. `t LABEL' Branch to LABEL only if there has been a successful `s'ubstitution since the last input line was read or `t' branch was taken. The LABEL may be omitted, in which case the next cycle is started. File: sed.info, Node: Examples, Next: Limitations, Prev: sed Programs, Up: Top Some sample scripts ******************* [[Not this release, sorry. But check out the scripts in the testsuite directory, and the amazing dc.sed script in the top-level directory of this distribution.]] File: sed.info, Node: Limitations, Next: Other Resources, Prev: Examples, Up: Top About the (non-)limitations on line length ****************************************** For those who want to write portable SED scripts, be aware that some implementations have been known to limit line lengths (for the pattern and hold spaces) to be no more than 4000 bytes. The POSIX.2 standard specifies that conforming SED implementations shall support at least 8192 byte line lengths. GNU SED has no built-in limit on line length; as long as SED can malloc() more (virtual) memory, it will allow lines as long as you care to feed it (or construct within it). File: sed.info, Node: Other Resources, Next: Reporting Bugs, Prev: Limitations, Up: Top Other resources for learning about SED ************************************** In addition to several books that have been written about SED (either specifically or as chapters in books which discuss shell programming), one can find out more about SED (including suggestions of a few books) from the FAQ for the seders mailing list, available from any of: `http://www.dbnet.ece.ntua.gr/~george/sed/sedfaq.html' `http://www.ptug.org/sed/sedfaq.htm' `http://www.wollery.demon.co.uk/sedtut10.txt' There is an informal "seders" mailing list manually maintained by Al Aab. To subscribe, send e-mail to <af137@torfree.net> with a brief description of your interest. File: sed.info, Node: Reporting Bugs, Next: Concept Index, Prev: Other Resources, Up: Top Reporting bugs ************** Email bug reports to <bug-gnu-utils@gnu.org>. Be sure to include the word "sed" somewhere in the "Subject:" field. File: sed.info, Node: Concept Index, Next: Command and Option Index, Prev: Reporting Bugs, Up: Top Concept Index ************* This is a general index of all issues discussed in this manual, with the exception of the SED commands and command-line options. * Menu: * Adding a block of text after a line: Other Commands. * Address, as a regular expression: Addresses. * Address, last line: Addresses. * Address, numeric: Addresses. * Addresses, in SED scripts: Addresses. * Addtional reading about SED: Other Resources. * Append hold space to pattern space: Other Commands. * Append next input line to pattern space: Other Commands. * Append pattern space to hold space: Other Commands. * Backreferences, in regular expressions: Common Commands. * Branch to a label, if s/// succeeded: Programming Commands. * Branch to a label, unconditionally: Programming Commands. * Buffer spaces, pattern and hold: Data Spaces. * Bugs, reporting: Reporting Bugs. * Case-insensitive matching: Common Commands. * Caveat -- #n on first line: Common Commands. * Caveat -- p command and -n flag: Common Commands. * Command groups: Common Commands. * Comments, in scripts: Common Commands. * Conditional branch: Programming Commands. * Copy hold space into pattern space: Other Commands. * Copy pattern space into hold space: Other Commands. * Delete first line from pattern space: Other Commands. * Deleting lines: Common Commands. * Exchange hold space with pattern space: Other Commands. * Excluding lines: Addresses. * Files to be processed as input: Invoking SED. * Flow of control in scripts: Programming Commands. * Global substitution: Common Commands. * GNU extensions, I modifier <1>: Common Commands. * GNU extensions, I modifier: Addresses. * GNU extensions, N~M addresses: Addresses. * GNU extensions, unlimited line length: Limitations. * Goto, in scripts: Programming Commands. * Grouping commands: Common Commands. * Hold space, appending from pattern space: Other Commands. * Hold space, appending to pattern space: Other Commands. * Hold space, copy into pattern space: Other Commands. * Hold space, copying pattern space into: Other Commands. * Hold space, definition: Data Spaces. * Hold space, exchange with pattern space: Other Commands. * Insert text from a file: Other Commands. * Inserting a block of text before a line: Other Commands. * Labels, in scripts: Programming Commands. * Last line, selecting: Addresses. * Line number, print: Other Commands. * Line selection: Addresses. * Line, selecting by number: Addresses. * Line, selecting by regular expression match: Addresses. * Line, selecting last: Addresses. * List pattern space: Other Commands. * Next input line, append to pattern space: Other Commands. * Next input line, replace pattern space with: Common Commands. * Parenthesized substrings: Common Commands. * Pattern space, definition: Data Spaces. * Portability, comments: Common Commands. * Portability, line length limitations: Limitations. * Portability, p command and -n flag: Common Commands. * Print first line from pattern space: Other Commands. * Print line number: Other Commands. * Print selected lines: Common Commands. * Print unambiguous representation of pattern space: Other Commands. * Printing text after substitution: Common Commands. * Quitting: Common Commands. * Range of lines: Addresses. * Read next input line: Common Commands. * Read text from a file: Other Commands. * Replace hold space with copy of pattern space: Other Commands. * Replace pattern space with copy of hold space: Other Commands. * Replace specific input lines: Other Commands. * Replacing all text matching regexp in a line: Common Commands. * Replacing only Nth match of regexp in a line: Common Commands. * Replacing text matching regexp: Common Commands. * Replacing text matching regexp, options: Common Commands. * Script structure: sed Programs. * Script, from a file: Invoking SED. * Script, from command line: Invoking SED. * SED program structure: sed Programs. * Selected lines, replacing: Other Commands. * Selecting lines to process: Addresses. * Selecting non-matching lines: Addresses. * Several lines, selecting: Addresses. * Slash character, in regular expressions: Addresses. * Spaces, pattern and hold: Data Spaces. * Standard input, processing as input: Invoking SED. * Stream editor: Introduction. * Substitution of text: Common Commands. * Substitution of text, options: Common Commands. * Text, appending: Other Commands. * Text, insertion: Other Commands. * Transliteration: Other Commands. * Usage summary, printing: Invoking SED. * Version, printing: Invoking SED. * Write result of a substitution to file: Common Commands. * Write to a file: Other Commands. File: sed.info, Node: Command and Option Index, Prev: Concept Index, Up: Top Command and Option Index ************************ This is an alphabetical list of all SED commands and command-line opions. * Menu: * # (comment) command: Common Commands. * --expression: Invoking SED. * --file: Invoking SED. * --help: Invoking SED. * --quiet: Invoking SED. * --silent: Invoking SED. * --version: Invoking SED. * -e: Invoking SED. * -f: Invoking SED. * -h: Invoking SED. * -n: Invoking SED. * -n, forcing from within a script: Common Commands. * -V: Invoking SED. * : (label) command: Programming Commands. * = (print line number) command: Other Commands. * a (append text lines) command: Other Commands. * b (branch) command: Programming Commands. * c (change to text lines) command: Other Commands. * D (delete first line) command: Other Commands. * d (delete) command: Common Commands. * G (appending Get) command: Other Commands. * g (get) command: Other Commands. * H (append Hold) command: Other Commands. * h (hold) command: Other Commands. * i (insert text lines) command: Other Commands. * l (list unambiguously) command: Other Commands. * N (append Next line) command: Other Commands. * n (next-line) command: Common Commands. * P (print first line) command: Other Commands. * p (print) command: Common Commands. * q (quit) command: Common Commands. * r (read file) command: Other Commands. * s (substitute) command: Common Commands. * s command, option flags: Common Commands. * t (conditional branch) command: Programming Commands. * w (write file) command: Other Commands. * x (eXchange) command: Other Commands. * y (transliterate) command: Other Commands. * {} command grouping: Common Commands. Tag Table: Node: Top1042 Node: Introduction1762 Node: Invoking SED2308 Node: sed Programs3751 Node: Addresses4736 Node: Regular Expressions7443 Node: Data Spaces7802 Node: Common Commands8325 Node: Other Commands12456 Node: Programming Commands16367 Node: Examples17266 Node: Limitations17560 Node: Other Resources18218 Node: Reporting Bugs19000 Node: Concept Index19248 Node: Command and Option Index24957 End Tag Table