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GNU Info File | 1996-10-12 | 50KB | 964 lines

This is Info file fileutils.info, produced by Makeinfo-1.64 from the input file /ade-src/fsf/fileutils/doc/fileutils.texi. START-INFO-DIR-ENTRY * File utilities: (fileutils). GNU file utilities. * chgrp: (fileutils)chgrp invocation. Change file groups. * chown: (fileutils)chown invocation. Change file owners/groups. * chmod: (fileutils)chmod invocation. Change file permissions. * cp: (fileutils)cp invocation. Copy files. * dd: (fileutils)dd invocation. Copy and convert a file. * df: (fileutils)df invocation. Report filesystem disk usage. * dir: (fileutils)dir invocation. List directories briefly. * dircolors: (fileutils)dircolors invocation. Color setup for ls. * du: (fileutils)du invocation. Report on disk usage. * install: (fileutils)install invocation. Copy and change attributes. * ln: (fileutils)ln invocation. Make links between files. * ls: (fileutils)ls invocation. List directory contents. * mkdir: (fileutils)mkdir invocation. Create directories. * mkfifo: (fileutils)mkfifo invocation. Create FIFOs: (named pipes). * mknod: (fileutils)mknod invocation. Create special files. * mv: (fileutils)mv invocation. Rename files. * rm: (fileutils)rm invocation. Remove files. * rmdir: (fileutils)rmdir invocation. Remove empty directories. * sync: (fileutils)sync invocation. Synchronize memory and disk. * touch: (fileutils)touch invocation. Change file timestamps. * vdir: (fileutils)vdir invocation. List directories verbosely. END-INFO-DIR-ENTRY This file documents the GNU set of file utilities. Copyright (C) 1994, 95, 96 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: fileutils.info, Node: Top, Next: Introduction, Up: (dir) GNU file utilities ****************** This manual minimally documents version 3.13 of the GNU file utilities. * Menu: * Introduction:: Caveats, overview, and authors. * Common options:: Common options. * File permissions:: Access modes. * Date input formats:: Specifying date strings. * Directory listing:: ls dir vdir d v dircolors * Basic operations:: cp dd install mv rm * Special file types:: ln mkdir rmdir mkfifo mknod * Changing file attributes:: chgrp chmod chown touch * Disk usage:: df du sync * Index:: General index. File: fileutils.info, Node: Introduction, Next: Common options, Prev: Top, Up: Top Introduction ************ This manual is incomplete: No attempt is made to explain basic file concepts in a way suitable for novices. Thus, if you are interested, please get involved in improving this manual. The entire GNU community will benefit. The GNU file utilities are mostly compatible with the POSIX.2 standard. Please report bugs to `bug-gnu-utils@prep.ai.mit.edu'. Remember to include the version number, machine architecture, input files, and any other information needed to reproduce the bug: your input, what you expected, what you got, and why it is wrong. Diffs are welcome, but please include a description of the problem as well, since this is sometimes difficult to infer. *Note Bugs: (gcc)Bugs. This manual is based on the Unix man pages in the distribution, which were originally written by David MacKenzie and updated by Jim Meyering. Franc,ois Pinard did the initial conversion to Texinfo format. Karl Berry did the indexing, some reorganization, and editing of the results. Richard Stallman contributed his usual invaluable insights to the overall process. File: fileutils.info, Node: Common options, Next: File permissions, Prev: Introduction, Up: Top Common options ************** Certain options are available in all of these programs (in fact, every GNU program should accept them). Rather than writing identical descriptions for each of the programs, they are described here. `--help' Print a usage message listing all available options, then exit successfully. `--version' Print the version number, then exit successfully. * Menu: * Backup options:: -b -S -V, in some programs. File: fileutils.info, Node: Backup options, Up: Common options Backup options ============== Some GNU programs (at least `cp', `install', `ln', and `mv') optionally make backups of files before writing new versions. These options control the details of these backups. The options are also briefly mentioned in the descriptions of the particular programs. `--backup' Make backups of files that are about to be overwritten or removed. Without this option, the original versions are destroyed. `-S SUFFIX' `--suffix=SUFFIX' Append SUFFIX to each backup file made with `-b'. If this option is not specified, the value of the `SIMPLE_BACKUP_SUFFIX' environment variable is used. And if `SIMPLE_BACKUP_SUFFIX' is not set, the default is `~', just as in Emacs. `-V METHOD' `--version-control=METHOD' Use METHOD to determine the type of backups made with `-b'. If this option is not specified, the value of the `VERSION_CONTROL' environment variable is used. And if `VERSION_CONTROL' is not set, the default backup type is `existing'. This option corresponds to the Emacs variable `version-control'; the same values for METHOD are accepted as in Emacs. This options also more descriptive name. The valid METHODs (unique abbreviations are accepted): `t' `numbered' Always make numbered backups. `nil' `existing' Make numbered backups of files that already have them, simple backups of the others. `never' `simple' Always make simple backups. File: fileutils.info, Node: File permissions, Next: Date input formats, Prev: Common options, Up: Top File permissions **************** Each file has a set of "permissions" that control the kinds of access that users have to that file. The permissions for a file are also called its "access mode". They can be represented either in symbolic form or as an octal number. * Menu: * Mode Structure:: Structure of file permissions. * Symbolic Modes:: Mnemonic permissions representation. * Numeric Modes:: Permissions as octal numbers. File: fileutils.info, Node: Mode Structure, Next: Symbolic Modes, Up: File permissions Structure of File Permissions ============================= There are three kinds of permissions that a user can have for a file: 1. permission to read the file. For directories, this means permission to list the contents of the directory. 2. permission to write to (change) the file. For directories, this means permission to create and remove files in the directory. 3. permission to execute the file (run it as a program). For directories, this means permission to access files in the directory. There are three categories of users who may have different permissions to perform any of the above operations on a file: 1. the file's owner; 2. other users who are in the file's group; 3. everyone else. Files are given an owner and group when they are created. Usually the owner is the current user and the group is the group of the directory the file is in, but this varies with the operating system, the filesystem the file is created on, and the way the file is created. You can change the owner and group of a file by using the `chown' and `chgrp' commands. In addition to the three sets of three permissions listed above, a file's permissions have three special components, which affect only executable files (programs) and, on some systems, directories: 1. set the process's effective user ID to that of the file upon execution (called the "setuid bit"). No effect on directories. 2. set the process's effective group ID to that of the file upon execution (called the "setgid bit"). For directories on some systems, put files created in the directory into the same group as the directory, no matter what group the user who creates them is in. 3. save the program's text image on the swap device so it will load more quickly when run (called the "sticky bit"). For directories on some systems, prevent users from removing files that they do not own in the directory; this is called making the directory "append-only". File: fileutils.info, Node: Symbolic Modes, Next: Numeric Modes, Prev: Mode Structure, Up: File permissions Symbolic Modes ============== "Symbolic modes" represent changes to files' permissions as operations on single-character symbols. They allow you to modify either all or selected parts of files' permissions, optionally based on their previous values, and perhaps on the current `umask' as well (*note Umask and Protection::.). The format of symbolic modes is: [ugoa...][[+-=][rwxXstugo...]...][,...] The following sections describe the operators and other details of symbolic modes. * Menu: * Setting Permissions:: Basic operations on permissions. * Copying Permissions:: Copying existing permissions. * Changing Special Permissions:: Special permissions. * Conditional Executability:: Conditionally affecting executability. * Multiple Changes:: Making multiple changes. * Umask and Protection:: The effect of the umask. File: fileutils.info, Node: Setting Permissions, Next: Copying Permissions, Up: Symbolic Modes Setting Permissions ------------------- The basic symbolic operations on a file's permissions are adding, removing, and setting the permission that certain users have to read, write, and execute the file. These operations have the following format: USERS OPERATION PERMISSIONS The spaces between the three parts above are shown for readability only; symbolic modes can not contain spaces. The USERS part tells which users' access to the file is changed. It consists of one or more of the following letters (or it can be empty; *note Umask and Protection::., for a description of what happens then). When more than one of these letters is given, the order that they are in does not matter. the user who owns the file; other users who are in the file's group; all other users; all users; the same as `ugo'. The OPERATION part tells how to change the affected users' access to the file, and is one of the following symbols: to add the PERMISSIONS to whatever permissions the USERS already have for the file; to remove the PERMISSIONS from whatever permissions the USERS already have for the file; to make the PERMISSIONS the only permissions that the USERS have for the file. The PERMISSIONS part tells what kind of access to the file should be changed; it is zero or more of the following letters. As with the USERS part, the order does not matter when more than one letter is given. Omitting the PERMISSIONS part is useful only with the `=' operation, where it gives the specified USERS no access at all to the file. the permission the USERS have to read the file; the permission the USERS have to write to the file; the permission the USERS have to execute the file. For example, to give everyone permission to read and write a file, but not to execute it, use: a=rw To remove write permission for from all users other than the file's owner, use: go-w The above command does not affect the access that the owner of the file has to it, nor does it affect whether other users can read or execute the file. To give everyone except a file's owner no permission to do anything with that file, use the mode below. Other users could still remove the file, if they have write permission on the directory it is in. go= Another way to specify the same thing is: og-rxw File: fileutils.info, Node: Copying Permissions, Next: Changing Special Permissions, Prev: Setting Permissions, Up: Symbolic Modes Copying Existing Permissions ---------------------------- You can base a file's permissions on its existing permissions. To do this, instead of using `r', `w', or `x' after the operator, you use the letter `u', `g', or `o'. For example, the mode o+g adds the permissions for users who are in a file's group to the permissions that other users have for the file. Thus, if the file started out as mode 664 (`rw-rw-r--'), the above mode would change it to mode 666 (`rw-rw-rw-'). If the file had started out as mode 741 (`rwxr----x'), the above mode would change it to mode 745 (`rwxr--r-x'). The `-' and `=' operations work analogously. File: fileutils.info, Node: Changing Special Permissions, Next: Conditional Executability, Prev: Copying Permissions, Up: Symbolic Modes Changing Special Permissions ---------------------------- In addition to changing a file's read, write, and execute permissions, you can change its special permissions. *Note Mode Structure::, for a summary of these permissions. To change a file's permission to set the user ID on execution, use `u' in the USERS part of the symbolic mode and `s' in the PERMISSIONS part. To change a file's permission to set the group ID on execution, use `g' in the USERS part of the symbolic mode and `s' in the PERMISSIONS part. To change a file's permission to stay permanently on the swap device, use `o' in the USERS part of the symbolic mode and `t' in the PERMISSIONS part. For example, to add set user ID permission to a program, you can use the mode: u+s To remove both set user ID and set group ID permission from it, you can use the mode: ug-s To cause a program to be saved on the swap device, you can use the mode: o+t Remember that the special permissions only affect files that are executable, plus, on some systems, directories (on which they have different meanings; *note Mode Structure::.). Using `a' in the USERS part of a symbolic mode does not cause the special permissions to be affected; thus, a+s has *no effect*. You must use `u', `g', and `o' explicitly to affect the special permissions. Also, the combinations `u+t', `g+t', and `o+s' have no effect. The `=' operator is not very useful with special permissions; for example, the mode: o=t does cause the file to be saved on the swap device, but it also removes all read, write, and execute permissions that users not in the file's group might have had for it. File: fileutils.info, Node: Conditional Executability, Next: Multiple Changes, Prev: Changing Special Permissions, Up: Symbolic Modes Conditional Executability ------------------------- There is one more special type of symbolic permission: if you use `X' instead of `x', execute permission is affected only if the file already had execute permission or is a directory. It affects directories' execute permission even if they did not initially have any execute permissions set. For example, this mode: a+X gives all users permission to execute files (or search directories) if anyone could before. File: fileutils.info, Node: Multiple Changes, Next: Umask and Protection, Prev: Conditional Executability, Up: Symbolic Modes Making Multiple Changes ----------------------- The format of symbolic modes is actually more complex than described above (*note Setting Permissions::.). It provides two ways to make multiple changes to files' permissions. The first way is to specify multiple OPERATION and PERMISSIONS parts after a USERS part in the symbolic mode. For example, the mode: og+rX-w gives users other than the owner of the file read permission and, if it is a directory or if someone already had execute permission to it, gives them execute permission; and it also denies them write permission to it file. It does not affect the permission that the owner of the file has for it. The above mode is equivalent to the two modes: og+rX og-w The second way to make multiple changes is to specify more than one simple symbolic mode, separated by commas. For example, the mode: a+r,go-w gives everyone permission to read the file and removes write permission on it for all users except its owner. Another example: u=rwx,g=rx,o= sets all of the non-special permissions for the file explicitly. (It gives users who are not in the file's group no permission at all for The two methods can be combined. The mode: a+r,g+x-w gives all users permission to read the file, and gives users who are in the file's group permission to execute it, as well, but not permission to write to it. The above mode could be written in several different ways; another is: u+r,g+rx,o+r,g-w File: fileutils.info, Node: Umask and Protection, Prev: Multiple Changes, Up: Symbolic Modes The Umask and Protection ------------------------ If the USERS part of a symbolic mode is omitted, it defaults to `a' (affect all users), except that any permissions that are *set* in the system variable `umask' are *not affected*. The value of `umask' can be set using the `umask' command. Its default value varies from system to system. Omitting the USERS part of a symbolic mode is generally not useful with operations other than `+'. It is useful with `+' because it allows you to use `umask' as an easily customizable protection against giving away more permission to files than you intended to. As an example, if `umask' has the value 2, which removes write permission for users who are not in the file's group, then the mode: +w adds permission to write to the file to its owner and to other users who are in the file's group, but *not* to other users. In contrast, the mode: a+w ignores `umask', and *does* give write permission for the file to all users. File: fileutils.info, Node: Numeric Modes, Prev: Symbolic Modes, Up: File permissions Numeric Modes ============= File permissions are stored internally as 16 bit integers. As an alternative to giving a symbolic mode, you can give an octal (base 8) number that corresponds to the internal representation of the new mode. This number is always interpreted in octal; you do not have to add a leading 0, as you do in C. Mode 0055 is the same as mode 55. A numeric mode is usually shorter than the corresponding symbolic mode, but it is limited in that it can not take into account a file's previous permissions; it can only set them absolutely. The permissions granted to the user, to other users in the file's group, and to other users not in the file's group are each stored as three bits, which are represented as one octal digit. The three special permissions are also each stored as one bit, and they are as a group represented as another octal digit. Here is how the bits are arranged in the 16 bit integer, starting with the lowest valued bit: Value in Corresponding Mode Permission Other users not in the file's group: 1 Execute 2 Write 4 Read Other users in the file's group: 10 Execute 20 Write 40 Read The file's owner: 100 Execute 200 Write 400 Read Special permissions: 1000 Save text image on swap device 2000 Set group ID on execution 4000 Set user ID on execution For example, numeric mode 4755 corresponds to symbolic mode `u=rwxs,go=rx', and numeric mode 664 corresponds to symbolic mode `ug=rw,o=r'. Numeric mode 0 corresponds to symbolic mode `ugo='. File: fileutils.info, Node: Date input formats, Next: Directory listing, Prev: File permissions, Up: Top Date input formats ****************** This section describes the textual date representations that GNU programs accept. These are the strings you, as a user, can supply as arguments to the various programs. The C interface (via the `getdate' function) is not described here. Although the date syntax here can represent any possible time since zero A.D., computer integers are not big enough for such a (comparatively) long time. The earliest date semantically allowed on Unix systems is midnight, 1 January 1970 UCT. * Menu: * General date syntax:: Common rules. * Calendar date item:: 19 Dec 1994. * Time of day item:: 9:20pm. * Timezone item:: EST, DST, BST, UCT, AHST, ... * Day of week item:: Monday and others. * Relative item in date strings:: next tuesday, 2 years ago. * Pure numbers in date strings:: 19931219, 1440. * Authors of getdate:: Bellovin, Salz, Berets, et al. File: fileutils.info, Node: General date syntax, Next: Calendar date item, Up: Date input formats General date syntax =================== A "date" is a string, possibly empty, containing many items separated by whitespace. The whitespace may be omitted when no ambiguity arises. The empty string means the beginning of today (i.e., midnight). Order of the items is immaterial. A date string may contain many flavors of items: * calendar date items * time of the day items * time zone items * day of the week items * relative items * pure numbers. We describe each of these item types in turn, below. A few numbers may be written out in words in most contexts. This is most useful for specifying day of the week items or relative items (see below). Here is the list: `first' for 1, `next' for 2, `third' for 3, `fourth' for 4, `fifth' for 5, `sixth' for 6, `seventh' for 7, `eighth' for 8, `ninth' for 9, `tenth' for 10, `eleventh' for 11 and `twelfth' for 12. Also, `last' means exactly -1. When a month is written this way, it is still considered to be written numerically, instead of being "spelled in full"; this changes the allowed strings. Alphabetic case is completely ignored in dates. Comments may be introduced between round parentheses, as long as included parentheses are properly nested. Hyphens not followed by a digit are currently ignored. Leading zeros on numbers are ignored. File: fileutils.info, Node: Calendar date item, Next: Time of day item, Prev: General date syntax, Up: Date input formats Calendar date item ================== A "calendar date item" specifies a day of the year. It is specified differently, depending on whether the month is specified numerically or literally. All these strings specify the same calendar date: 1970-09-17 # ISO 8601. 70-9-17 # This century assumed by default. 70-09-17 # Leading zeros are ignored. 9/17/72 # Common U.S. writing. 24 September 1972 24 Sept 72 # September has a special abbreviation. 24 Sep 72 # Three-letter abbreviations always allowed. Sep 24, 1972 24-sep-72 24sep72 The year can also be omitted. In this case, the last specified year is used, or the current year if none. For example: 9/17 sep 17 Here are the rules. For numeric months, the ISO 8601 format `YEAR-MONTH-DAY' is allowed, where YEAR is any positive number, MONTH is a number between 01 and 12, and DAY is a number between 01 and 31. A leading zero must be present if a number is less than ten. If YEAR is less than 100, then 1900 is added to it to force a date in this century. The construct `MONTH/DAY/YEAR', popular in the United States, is accepted. Also `MONTH/DAY', omitting the year. Literal months may be spelled out in full: `January', `February', `March', `April', `May', `June', `July', `August', `September', `October', `November' or `December'. Literal months may be abbreviated to their first three letters, possibly followed by an abbreviating dot. It is also permitted to write `Sept' instead of `September'. When months are written literally, the calendar date may be given as any of the following: DAY MONTH YEAR DAY MONTH MONTH DAY YEAR DAY-MONTH-YEAR Or, omitting the year: MONTH DAY File: fileutils.info, Node: Time of day item, Next: Timezone item, Prev: Calendar date item, Up: Date input formats Time of day item ================ A "time of day item" in date strings specifies the time on a given day. Here are some examples, all of which represent the same time: 20:02:0 20:02 8:02pm 20:02-0500 # In EST (Eastern U.S. Standard Time). More generally, the time of the day may be given as `HOUR:MINUTE:SECOND', where HOUR is a number between 0 and 23, MINUTE is a number between 0 and 59, and SECOND is a number between 0 and 59. Alternatively, `:SECOND' can be omitted, in which case it is taken to be zero. If the time is followed by `am' or `pm' (or `a.m.' or `p.m.'), HOUR is restricted to run from 1 to 12, and `:MINUTE' may be omitted (taken to be zero). `am' indicates the first half of the day, `pm' indicates the second half of the day. In this notation, 12 is the predecessor of 1: midnight is `12am' while noon is `12pm'. The time may alternatively be followed by a timezone correction, expressed as `SHHMM', where S is `+' or `-', HH is a number of zone hours and MM is a number of zone minutes. When a timezone correction is given this way, it forces interpretation of the time in UTC, overriding any previous specification for the timezone or the local timezone. The MINUTE part of the time of the day may not be elided when a timezone correction is used. This is the only way to specify a timezone correction by fractional parts of an hour. Either `am'/`pm' or a timezone correction may be specified, but not both. File: fileutils.info, Node: Timezone item, Next: Day of week item, Prev: Time of day item, Up: Date input formats Timezone item ============= A "timezone item" specifies an international timezone, indicated by a small set of letters. Any included period is ignored. Military timezone designations use a single letter. Currently, only integral zone hours may be represented in a timezone item. See the previous section for a finer control over the timezone correction. Here are many non-daylight-savings-time timezones, indexed by the zone hour value. `GMT' for Greenwich Mean, `UT' or `UTC' for Universal (Coordinated), `WET' for Western European and `Z' for militaries. `WAT' for West Africa and `A' for militaries. `AT' for Azores and `B' for militaries. `C' for militaries. `AST' for Atlantic Standard and `D' for militaries. `E' for militaries and `EST' for Eastern Standard. `CST' for Central Standard and `F' for militaries. `G' for militaries and `MST' for Mountain Standard. `H' for militaries and `PST' for Pacific Standard. `I' for militaries and `YST' for Yukon Standard. +1000 `AHST' for Alaska-Hawaii Standard, `CAT' for Central Alaska, `HST' for Hawaii Standard and `K' for militaries. +1100 `L' for militaries and `NT' for Nome. +1200 `IDLW' for International Date Line West and `M' for militaries. `CET' for Central European, `FWT' for French Winter, `MET' for Middle European, `MEWT' for Middle European Winter, `N' for militaries and `SWT' for Swedish Winter. `EET' for Eastern European, USSR Zone 1 and `O' for militaries. `BT' for Baghdad, USSR Zone 2 and `P' for militaries. `Q' for militaries and `ZP4' for USSR Zone 3. `R' for militaries and `ZP5' for USSR Zone 4. `S' for militaries and `ZP6' for USSR Zone 5. `T' for militaries and `WAST' for West Australian Standard. `CCT' for China Coast, USSR Zone 7 and `U' for militaries. `JST' for Japan Standard, USSR Zone 8 and `V' for militaries. -1000 `EAST' for East Australian Standard, `GST' for Guam Standard, USSR Zone 9 and `W' for militaries. -1100 `X' for militaries. -1200 `IDLE' for International Date Line East, `NZST' for New Zealand Standard, `NZT' for New Zealand and `Y' for militaries. Here are many DST timezones, indexed by the zone hour value. Also, by following a non-DST timezone by the string `DST' in a separate word (that is, separated by some whitespace), the corresponding DST timezone may be specified. `BST' for British Summer. `ADT' for Atlantic Daylight. `EDT' for Eastern Daylight. `CDT' for Central Daylight. `MDT' for Mountain Daylight. `PDT' for Pacific Daylight. `YDT' for Yukon Daylight. +1000 `HDT' for Hawaii Daylight. `MEST' for Middle European Summer, `MESZ' for Middle European Summer, `SST' for Swedish Summer and `FST' for French Summer. `WADT' for West Australian Daylight. -1000 `EADT' for Eastern Australian Daylight. -1200 `NZDT' for New Zealand Daylight. File: fileutils.info, Node: Day of week item, Next: Relative item in date strings, Prev: Timezone item, Up: Date input formats Day of week item ================ The explicit mention of a day of the week will forward the date (only if necessary) to reach that day of the week in the future. Days of the week may be spelled out in full: `Sunday', `Monday', `Tuesday', `Wednesday', `Thursday', `Friday' or `Saturday'. Days may be abbreviated to their first three letters, optionally followed by a period. The special abbreviations `Tues' for `Tuesday', `Wednes' for `Wednesday' and `Thur' or `Thurs' for `Thursday' are also allowed. A number may precede a day of the week item to move forward supplementary weeks. It is best used in expression like `third monday'. In this context, `last DAY' or `next DAY' is also acceptable; they move one week before or after the day that DAY by itself would represent. A comma following a day of the week item is ignored. File: fileutils.info, Node: Relative item in date strings, Next: Pure numbers in date strings, Prev: Day of week item, Up: Date input formats Relative item in date strings ============================= "Relative items" adjust a date (or the current date if none) forward or backward. The effects of relative items accumulate. Here are some examples: 1 year 1 year ago 3 years 2 days The unit of time displacement may be selected by the string `year' or `month' for moving by whole years or months. These are fuzzy units, as years and months are not all of equal duration. More precise units are `fortnight' which is worth 14 days, `week' worth 7 days, `day' worth 24 hours, `hour' worth 60 minutes, `minute' or `min' worth 60 seconds, and `second' or `sec' worth one second. An `s' suffix on these units is accepted and ignored. The unit of time may be preceded by a multiplier, given as an optionally signed number. Unsigned numbers are taken as positively signed. No number at all implies 1 for a multiplier. Following a relative item by the string `ago' is equivalent to preceding the unit by a multiplicator with value -1. The string `tomorrow' is worth one day in the future (equivalent to `day'), the string `yesterday' is worth one day in the past (equivalent to `day ago'). The strings `now' or `today' are relative items corresponding to zero-valued time displacement, these strings come from the fact a zero-valued time displacement represents the current time when not otherwise change by previous items. They may be used to stress other items, like in `12:00 today'. The string `this' also has the meaning of a zero-valued time displacement, but is preferred in date strings like `this thursday'. When a relative item makes the resulting date to cross the boundary between DST and non-DST (or vice-versa), the hour is adjusted according to the local time. File: fileutils.info, Node: Pure numbers in date strings, Next: Authors of getdate, Prev: Relative item in date strings, Up: Date input formats Pure numbers in date strings ============================ The precise intepretation of a pure decimal number is dependent of the context in the date string. If the decimal number is of the form YYYYMMDD and no other calendar date item (*note Calendar date item::.) appears before it in the date string, then YYYY is read as the year, MM as the month number and DD as the day of the month, for the specified calendar date. If the decimal number is of the form HHMM and no other time of day item appears before it in the date string, then HH is read as the hour of the day and MM as the minute of the hour, for the specified time of the day. MM can also be omitted. If both a calendar date and a time of day appear to the left of a number in the date string, but no relative item, then the number overrides the year. File: fileutils.info, Node: Authors of getdate, Prev: Pure numbers in date strings, Up: Date input formats Authors of `getdate' ==================== `getdate' was originally implemented by Steven M. Bellovin (`smb@research.att.com') while at the University of North Carolina at Chapel Hill. The code was later tweaked by a couple of people on Usenet, then completely overhauled by Rich $alz (`rsalz@bbn.com') and Jim Berets (`jberets@bbn.com') in August, 1990. Various revisions for the GNU system were made by David MacKenzie, Jim Meyering, and others. This chapter was originally produced by Franc,ois Pinard (`pinard@iro.umontreal.ca') from the `getdate.y' source code, and then edited by K. Berry (`kb@cs.umb.edu'). File: fileutils.info, Node: Directory listing, Next: Basic operations, Prev: Date input formats, Up: Top Directory listing ***************** This chapter describes the `ls' command and its variants `dir' and `vdir', which list information about files. * Menu: * ls invocation:: List directory contents. * dir invocation:: Briefly ls. * vdir invocation:: Verbosely ls. * dircolors invocation:: Color setup for ls, etc. File: fileutils.info, Node: ls invocation, Next: dir invocation, Up: Directory listing `ls': List directory contents ============================= The `ls' program lists information about files (of any type, including directories). Options and file arguments can be intermixed arbitrarily, as usual. For non-option command-line arguments that are directories, by default `ls' lists the contents of directories, not recursively, and omitting files with names beginning with `.'. For other non-option arguments, by default `ls' lists just the file name. If no non-option arguments are specified, `ls' lists the contents of the current directory. By default, the output is sorted alphabetically. If standard output is a terminal, the output is in columns (sorted vertically); otherwise, they are listed one per line. Because `ls' is such a fundamental program, it has accumulated many options over the years. They are described in the subsections below; within each section, options are listed alphabetically (ignoring case). The division of options into the subsections is not absolute, since some options affect more than one aspect of `ls''s operation. The `-g' option is accepted but ignored, for compatibility with Unix. Also see *Note Common options::. * Menu: * Which files are listed:: * What information is listed:: * Sorting the output:: * General output formatting:: * Formatting the file names:: File: fileutils.info, Node: Which files are listed, Next: What information is listed, Up: ls invocation Which files are listed ---------------------- These options determine which files `ls' lists information for. By default, any files and the contents of any directories on the command line are shown. `--all' List all files in directories, including files that start with `.'. `--almost-all' List all files in directories except for `.' and `..'. `--ignore-backups' Do not list files that end with `~', unless they are given on the command line. `--directory' List just the names of directories, as with other types of files, rather than listing their contents. `--ignore' Do not list files whose names match the shell pattern (not regular expression) PATTERN unless they are given on the command line. As in the shell, an initial `.' in a file name does not match a wildcard at the start of PATTERN. `--dereference' List the files linked to by symbolic links instead of listing the contents of the links. `--recursive' List the contents of all directories recursively. File: fileutils.info, Node: What information is listed, Next: Sorting the output, Prev: Which files are listed, Up: ls invocation What information is listed -------------------------- These options affect the information that `ls' displays. By default, only file names are shown. `--dired' With the long listing (`-l') format, print an additional line after the main output: //DIRED// BEG1 END1 BEG2 END2 ... The BEGN and ENDN are unsigned integers which record the byte position of the beginning and end of each file name in the output. This makes it easy for Emacs to find the names, even when they contain unusual characters such as space or newline, without fancy searching. If directories are being listed recursively (`-R'), output a similar line after each subdirectory: //SUBDIRED// BEG1 END1 ... `--no-group' Inhibit display of group information in a long format directory listing. (This is the default in some non-GNU versions of `ls', so we provide this option for compatibility.) `--inode' Print the inode number (also called the file serial number and index number) of each file to the left of the file name. (This number uniquely identifies each file within a particular filesystem.) `--format=long' `--format=verbose' In addition to the name of each file, print the file type, permissions, number of hard links, owner name, group name, size in bytes, and timestamp (by default, the modification time). For files with a time more than six months old or more than one hour into the future, the timestamp contains the year instead of the time of day. For each directory that is listed, preface the files with a line `total BLOCKS', where BLOCKS is the total disk space used by all files in that directory. By default, 1024-byte blocks are used; if the environment variable `POSIXLY_CORRECT' is set, 512-byte blocks are used (unless the `-k' option is given). The BLOCKS computed counts each hard link separately; this is arguably a deficiency. The permissions listed are similar to symbolic mode specifications (*note Symbolic Modes::.). But `ls' combines multiple bits into the third character of each set of permissions as follows: `s' If the setuid or setgid bit and the corresponding executable bit are both set. `S' If the setuid or setgid bit is set but the corresponding executable bit is not set. `t' If the sticky bit and the other-executable bit are both set. `T' If the sticky bit is set but the other-executable bit is not set. `x' If the executable bit is set and none of the above apply. `-' Otherwise. Produce long format directory listings, but don't display group information. It is equivalent to using `--format=long' with `--no-group' . This option is provided for compatibility with other versions of `ls'. `--size' Print the size of each file in 1024-byte blocks to the left of the file name. If the environment variable `POSIXLY_CORRECT' is set, 512-byte blocks are used instead, unless the `-k' option is given (*note General output formatting::.). For files that are NFS-mounted from an HP-UX system to a BSD system, this option reports sizes that are half the correct values. On HP-UX systems, it reports sizes that are twice the correct values for files that are NFS-mounted from BSD systems. This is due to a flaw in HP-UX; it also affects the HP-UX `ls' program. File: fileutils.info, Node: Sorting the output, Next: General output formatting, Prev: What information is listed, Up: ls invocation Sorting the output ------------------ These options change the order in which `ls' sorts the information it outputs. By default, sorting is done by character code (e.g., ASCII order). `--time=ctime' `--time=status' Sort according to the status change time (the `ctime' in the inode). If the long listing format (`-l') is being used, print the status change time instead of the modification time. Primarily, like `-U'--do not sort; list the files in whatever order they are stored in the directory. But also enable `-a' (list all files) and disable `-l', `--color', and `-s' (if they were specified before the `-f'). `--reverse' Reverse whatever the sorting method is--e.g., list files in reverse alphabetical order, youngest first, smallest first, or whatever. `--sort=size' Sort by file size, largest first. `--sort=time' Sort by modification time (the `mtime' in the inode), newest first. `--time=atime' `--time=access' `--time=use' Sort by access time (the `atime' in the inode). If the long listing format is being used, print the last access time. `--sort=none' Do not sort; list the files in whatever order they are stored in the directory. (Do not do any of the other unrelated things that `-f' does.) This is especially useful when listing very large directories, since not doing any sorting can be noticeably faster. `--sort=extension' Sort directory contents alphabetically by file extension (characters after the last `.'); files with no extension are sorted first. File: fileutils.info, Node: General output formatting, Next: Formatting the file names, Prev: Sorting the output, Up: ls invocation General output formatting ------------------------- These options affect the appearance of the overall output. `--format=single-column' List one file per line. This is the default for `ls' when standard output is not a terminal. `--format=vertical' List files in columns, sorted vertically. This is the default for `ls' if standard output is a terminal. It is always the default for the `dir' and `d' programs. `--color [=WHEN]' Specify whether to use color for distinguishing file types. WHEN may be omitted, or one of: * none Do not use color at all. This is the default. * auto Only use color if standard output is a terminal. * always Always use color. Specifying `--color' and no WHEN is equivalent to `--color=always'. `--classify' Append a character to each file name indicating the file type. Also, for regular files that are executable, append `*'. The file type indicators are `/' for directories, `@' for symbolic links, `|' for FIFOs, `=' for sockets, and nothing for regular files. `--full-time' List times in full, rather than using the standard abbreviation heuristics. The format is the same as `date''s default; it's not possible to change this, but you can extract out the date string with `cut' and then pass the result to `date -d'. *Note `date' invocation: (sh-utils)date invocation. This is most useful because the time output includes the seconds. (Unix filesystems store file timestamps only to the nearest second, so this option shows all the information there is.) For example, this can help when you have a Makefile that is not regenerating files properly. `--kilobytes' If file sizes are being listed, print them in kilobytes. This overrides the environment variable `POSIXLY_CORRECT'. `--format=commas' List files horizontally, with as many as will fit on each line, separated by `, ' (a comma and a space). `--numeric-uid-gid' List the numeric UID and GID instead of the names. Append a character to each file name indicating the file type. This is like `-F', except that executables are not marked. `-x FORMAT' `--format=across' `--format=horizontal' List the files in columns, sorted horizontally. `-T COLS' `--tabsize=COLS' Assume that each tabstop is COLS columns wide. The default is 8. `ls' uses tabs where possible in the output, for efficiency. If COLS is zero, do not use tabs at all. `--width=COLS' Assume the screen is COLS columns wide. The default is taken from the terminal settings if possible; otherwise the environment variable `COLUMNS' is used if it is set; otherwise the default is 80. File: fileutils.info, Node: Formatting the file names, Prev: General output formatting, Up: ls invocation Formatting the file names ------------------------- These options change how file names themselves are printed. `--escape' Quote nongraphic characters in file names using alphabetic and octal backslash sequences like those used in C. `--literal' Do not quote file names. `--hide-control-chars' Print question marks instead of nongraphic characters in file names. This is the default. `--quote-name' Enclose file names in double quotes and quote nongraphic characters as in C. File: fileutils.info, Node: dir invocation, Next: vdir invocation, Prev: ls invocation, Up: Directory listing `dir': Briefly list directory contents ====================================== `dir' (also installed as `d') is equivalent to `ls -C'; that is, files are by default listed in columns, sorted vertically. *Note `ls': ls invocation. File: fileutils.info, Node: vdir invocation, Next: dircolors invocation, Prev: dir invocation, Up: Directory listing `vdir': Verbosely list directory contents ========================================= `vdir' (also installed as `v')is equivalent to `ls -l'; that is, files are by default listed in long format. File: fileutils.info, Node: dircolors invocation, Prev: vdir invocation, Up: Directory listing `dircolors': Color setup for `ls' ================================= `dircolors' outputs a sequence of shell commands to set up the terminal for color output from `ls' (and `dir', etc.). Typical usage: eval `dircolors [OPTION]... [FILE]` If FILE is specified, `dircolors' reads it to determine which colors to use for which file types and extensions. Otherwise, a precompiled database is used. For details on the format of these files, run `dircolors --print-data-base'. The output is a shell command to set the `LS_COLOR' environment variable. You can specify the shell syntax to use on the command line, or `dircolors' will guess it from the value of the `SHELL' environment variable. The program accepts the following options. Also see *Note Common options::. `--sh' `--bourne-shell' Output Bourne shell commands. This is the default if the `SHELL' environment variable is set and does not end with `csh' or `tcsh'. `--csh' `--c-shell' Output C shell commands. This is the default if `SHELL' ends with `csh' or `tcsh'. `--print-data-base' Print the (compiled-in) default color configuration database. This output is itself a valid configuration file, and is fairly descriptive of the possibilities. File: fileutils.info, Node: Basic operations, Next: Special file types, Prev: Directory listing, Up: Top Basic operations **************** This chapter describes the commands for basic file manipulation: copying, moving (renaming), and deleting (removing). * Menu: * cp invocation:: Copy files. * dd invocation:: Convert and copy a file. * install invocation:: Copy files and set attributes. * mv invocation:: Move (rename) files. * rm invocation:: Remove files or directories.