|
HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|
|
PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
|
|
|
FIND(1P) POSIX Programmer's Manual FIND(1P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
find — find files
find [-H|-L] path... [operand_expression...]
The find utility shall recursively descend the directory
hierarchy from each file specified by path, evaluating a Boolean
expression composed of the primaries described in the OPERANDS
section for each file encountered. Each path operand shall be
evaluated unaltered as it was provided, including all trailing
<slash> characters; all pathnames for other files encountered in
the hierarchy shall consist of the concatenation of the current
path operand, a <slash> if the current path operand did not end
in one, and the filename relative to the path operand. The
relative portion shall contain no dot or dot-dot components, no
trailing <slash> characters, and only single <slash> characters
between pathname components.
The find utility shall be able to descend to arbitrary depths in
a file hierarchy and shall not fail due to path length
limitations (unless a path operand specified by the application
exceeds {PATH_MAX} requirements).
The find utility shall detect infinite loops; that is, entering a
previously visited directory that is an ancestor of the last file
encountered. When it detects an infinite loop, find shall write
a diagnostic message to standard error and shall either recover
its position in the hierarchy or terminate.
If a file is removed from or added to the directory hierarchy
being searched it is unspecified whether or not find includes
that file in its search.
The find utility shall conform to the Base Definitions volume of
POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
The following options shall be supported by the implementation:
-H Cause the file information and file type evaluated for
each symbolic link encountered as a path operand on the
command line to be those of the file referenced by the
link, and not the link itself. If the referenced file
does not exist, the file information and type shall be
for the link itself. File information and type for
symbolic links encountered during the traversal of a
file hierarchy shall be that of the link itself.
-L Cause the file information and file type evaluated for
each symbolic link encountered as a path operand on the
command line or encountered during the traversal of a
file hierarchy to be those of the file referenced by
the link, and not the link itself. If the referenced
file does not exist, the file information and type
shall be for the link itself.
Specifying more than one of the mutually-exclusive options -H and
-L shall not be considered an error. The last option specified
shall determine the behavior of the utility. If neither the -H
nor the -L option is specified, then the file information and
type for symbolic links encountered as a path operand on the
command line or encountered during the traversal of a file
hierarchy shall be that of the link itself.
The following operands shall be supported:
The first operand and subsequent operands up to but not including
the first operand that starts with a '-', or is a '!' or a '(',
shall be interpreted as path operands. If the first operand
starts with a '-', or is a '!' or a '(', the behavior is
unspecified. Each path operand is a pathname of a starting point
in the file hierarchy.
The first operand that starts with a '-', or is a '!' or a '(',
and all subsequent arguments shall be interpreted as an
expression made up of the following primaries and operators. In
the descriptions, wherever n is used as a primary argument, it
shall be interpreted as a decimal integer optionally preceded by
a <plus-sign> ('+') or <hyphen-minus> ('-'), as follows:
+n More than n.
n Exactly n.
-n Less than n.
The following primaries shall be supported:
-name pattern
The primary shall evaluate as true if the basename of
the current pathname matches pattern using the pattern
matching notation described in Section 2.13, Pattern
Matching Notation. The additional rules in Section
2.13.3, Patterns Used for Filename Expansion do not
apply as this is a matching operation, not an
expansion.
-path pattern
The primary shall evaluate as true if the current
pathname matches pattern using the pattern matching
notation described in Section 2.13, Pattern Matching
Notation. The additional rules in Section 2.13.3,
Patterns Used for Filename Expansion do not apply as
this is a matching operation, not an expansion.
-nouser The primary shall evaluate as true if the file belongs
to a user ID for which the getpwuid() function defined
in the System Interfaces volume of POSIX.1‐2017 (or
equivalent) returns NULL.
-nogroup The primary shall evaluate as true if the file belongs
to a group ID for which the getgrgid() function defined
in the System Interfaces volume of POSIX.1‐2017 (or
equivalent) returns NULL.
-xdev The primary shall always evaluate as true; it shall
cause find not to continue descending past directories
that have a different device ID (st_dev, see the stat()
function defined in the System Interfaces volume of
POSIX.1‐2017). If any -xdev primary is specified, it
shall apply to the entire expression even if the -xdev
primary would not normally be evaluated.
-prune The primary shall always evaluate as true; it shall
cause find not to descend the current pathname if it is
a directory. If the -depth primary is specified, the
-prune primary shall have no effect.
-perm [-]mode
The mode argument is used to represent file mode bits.
It shall be identical in format to the symbolic_mode
operand described in chmod, and shall be interpreted as
follows. To start, a template shall be assumed with all
file mode bits cleared. An op symbol of '+' shall set
the appropriate mode bits in the template; '-' shall
clear the appropriate bits; '=' shall set the
appropriate mode bits, without regard to the contents
of the file mode creation mask of the process. The op
symbol of '-' cannot be the first character of mode;
this avoids ambiguity with the optional leading
<hyphen-minus>. Since the initial mode is all bits
off, there are not any symbolic modes that need to use
'-' as the first character.
If the <hyphen-minus> is omitted, the primary shall
evaluate as true when the file permission bits exactly
match the value of the resulting template.
Otherwise, if mode is prefixed by a <hyphen-minus>, the
primary shall evaluate as true if at least all the bits
in the resulting template are set in the file
permission bits.
-perm [-]onum
If the <hyphen-minus> is omitted, the primary shall
evaluate as true when the file mode bits exactly match
the value of the octal number onum (see the description
of the octal mode in chmod). Otherwise, if onum is
prefixed by a <hyphen-minus>, the primary shall
evaluate as true if at least all of the bits specified
in onum are set. In both cases, the behavior is
unspecified when onum exceeds 07777.
-type c The primary shall evaluate as true if the type of the
file is c, where c is 'b', 'c', 'd', 'l', 'p', 'f', or
's' for block special file, character special file,
directory, symbolic link, FIFO, regular file, or
socket, respectively.
-links n The primary shall evaluate as true if the file has n
links.
-user uname
The primary shall evaluate as true if the file belongs
to the user uname. If uname is a decimal integer and
the getpwnam() (or equivalent) function does not return
a valid user name, uname shall be interpreted as a user
ID.
-group gname
The primary shall evaluate as true if the file belongs
to the group gname. If gname is a decimal integer and
the getgrnam() (or equivalent) function does not return
a valid group name, gname shall be interpreted as a
group ID.
-size n[c]
The primary shall evaluate as true if the file size in
bytes, divided by 512 and rounded up to the next
integer, is n. If n is followed by the character 'c',
the size shall be in bytes.
-atime n The primary shall evaluate as true if the file access
time subtracted from the initialization time, divided
by 86400 (with any remainder discarded), is n.
-ctime n The primary shall evaluate as true if the time of last
change of file status information subtracted from the
initialization time, divided by 86400 (with any
remainder discarded), is n.
-mtime n The primary shall evaluate as true if the file
modification time subtracted from the initialization
time, divided by 86400 (with any remainder discarded),
is n.
-exec utility_name [argument ...] ;
-exec utility_name [argument ...] {} +
The end of the primary expression shall be punctuated
by a <semicolon> or by a <plus-sign>. Only a <plus-
sign> that immediately follows an argument containing
only the two characters "{}" shall punctuate the end of
the primary expression. Other uses of the <plus-sign>
shall not be treated as special.
If the primary expression is punctuated by a
<semicolon>, the utility utility_name shall be invoked
once for each pathname and the primary shall evaluate
as true if the utility returns a zero value as exit
status. A utility_name or argument containing only the
two characters "{}" shall be replaced by the current
pathname. If a utility_name or argument string contains
the two characters "{}", but not just the two
characters "{}", it is implementation-defined whether
find replaces those two characters or uses the string
without change.
If the primary expression is punctuated by a <plus-
sign>, the primary shall always evaluate as true, and
the pathnames for which the primary is evaluated shall
be aggregated into sets. The utility utility_name shall
be invoked once for each set of aggregated pathnames.
Each invocation shall begin after the last pathname in
the set is aggregated, and shall be completed before
the find utility exits and before the first pathname in
the next set (if any) is aggregated for this primary,
but it is otherwise unspecified whether the invocation
occurs before, during, or after the evaluations of
other primaries. If any invocation returns a non-zero
value as exit status, the find utility shall return a
non-zero exit status. An argument containing only the
two characters "{}" shall be replaced by the set of
aggregated pathnames, with each pathname passed as a
separate argument to the invoked utility in the same
order that it was aggregated. The size of any set of
two or more pathnames shall be limited such that
execution of the utility does not cause the system's
{ARG_MAX} limit to be exceeded. If more than one
argument containing the two characters "{}" is present,
the behavior is unspecified.
The current directory for the invocation of
utility_name shall be the same as the current directory
when the find utility was started. If the utility_name
names any of the special built-in utilities (see
Section 2.14, Special Built-In Utilities), the results
are undefined.
-ok utility_name [argument ...] ;
The -ok primary shall be equivalent to -exec, except
that the use of a <plus-sign> to punctuate the end of
the primary expression need not be supported, and find
shall request affirmation of the invocation of
utility_name using the current file as an argument by
writing to standard error as described in the STDERR
section. If the response on standard input is
affirmative, the utility shall be invoked. Otherwise,
the command shall not be invoked and the value of the
-ok operand shall be false.
-print The primary shall always evaluate as true; it shall
cause the current pathname to be written to standard
output.
-newer file
The primary shall evaluate as true if the modification
time of the current file is more recent than the
modification time of the file named by the pathname
file.
-depth The primary shall always evaluate as true; it shall
cause descent of the directory hierarchy to be done so
that all entries in a directory are acted on before the
directory itself. If a -depth primary is not specified,
all entries in a directory shall be acted on after the
directory itself. If any -depth primary is specified,
it shall apply to the entire expression even if the
-depth primary would not normally be evaluated.
The primaries can be combined using the following operators (in
order of decreasing precedence):
( expression )
True if expression is true.
! expression
Negation of a primary; the unary NOT operator.
expression [-a] expression
Conjunction of primaries; the AND operator is implied
by the juxtaposition of two primaries or made explicit
by the optional -a operator. The second expression
shall not be evaluated if the first expression is
false.
expression -o expression
Alternation of primaries; the OR operator. The second
expression shall not be evaluated if the first
expression is true.
If no expression is present, -print shall be used as the
expression. Otherwise, if the given expression does not contain
any of the primaries -exec, -ok, or -print, the given expression
shall be effectively replaced by:
( given_expression ) -print
The -user, -group, and -newer primaries each shall evaluate their
respective arguments only once.
When the file type evaluated for the current file is a symbolic
link, the results of evaluating the -perm primary are
implementation-defined.
If the -ok primary is used, the response shall be read from the
standard input. An entire line shall be read as the response.
Otherwise, the standard input shall not be used.
None.
The following environment variables shall affect the execution of
find:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base
Definitions volume of POSIX.1‐2017, Section 8.2,
Internationalization Variables for the precedence of
internationalization variables used to determine the
values of locale categories.)
LC_ALL If set to a non-empty string value, override the values
of all the other internationalization variables.
LC_COLLATE
Determine the locale for the behavior of ranges,
equivalence classes, and multi-character collating
elements used in the pattern matching notation for the
-n option and in the extended regular expression
defined for the yesexpr locale keyword in the
LC_MESSAGES category.
LC_CTYPE This variable determines the locale for the
interpretation of sequences of bytes of text data as
characters (for example, single-byte as opposed to
multi-byte characters in arguments), the behavior of
character classes within the pattern matching notation
used for the -n option, and the behavior of character
classes within regular expressions used in the extended
regular expression defined for the yesexpr locale
keyword in the LC_MESSAGES category.
LC_MESSAGES
Determine the locale used to process affirmative
responses, and the locale used to affect the format and
contents of diagnostic messages and prompts written to
standard error.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
PATH Determine the location of the utility_name for the
-exec and -ok primaries, as described in the Base
Definitions volume of POSIX.1‐2017, Chapter 8,
Environment Variables.
Default.
The -print primary shall cause the current pathnames to be
written to standard output. The format shall be:
"%s\n", <path>
The -ok primary shall write a prompt to standard error containing
at least the utility_name to be invoked and the current pathname.
In the POSIX locale, the last non-<blank> in the prompt shall be
'?'. The exact format used is unspecified.
Otherwise, the standard error shall be used only for diagnostic
messages.
None.
None.
The following exit values shall be returned:
0 All path operands were traversed successfully.
>0 An error occurred.
Default.
The following sections are informative.
When used in operands, pattern matching notation, <semicolon>,
<left-parenthesis>, and <right-parenthesis> characters are
special to the shell and must be quoted (see Section 2.2,
Quoting).
The bit that is traditionally used for sticky (historically
01000) is specified in the -perm primary using the octal number
argument form. Since this bit is not defined by this volume of
POSIX.1‐2017, applications must not assume that it actually
refers to the traditional sticky bit.
1. The following commands are equivalent:
find .
find . -print
They both write out the entire directory hierarchy from the
current directory.
2. The following command:
find / \( -name tmp -o -name '*.xx' \) -atime +7 -exec rm {} \;
removes all files named tmp or ending in .xx that have not
been accessed for seven or more 24-hour periods.
3. The following command:
find . -perm -o+w,+s
prints (-print is assumed) the names of all files in or below
the current directory, with all of the file permission bits
S_ISUID, S_ISGID, and S_IWOTH set.
4. The following command:
find . -name SCCS -prune -o -print
recursively prints pathnames of all files in the current
directory and below, but skips directories named SCCS and
files in them.
5. The following command:
find . -print -name SCCS -prune
behaves as in the previous example, but prints the names of
the SCCS directories.
6. The following command is roughly equivalent to the -nt
extension to test:
if [ -n "$(find file1 -prune -newer file2)" ]; then
printf %s\\n "file1 is newer than file2"
fi
7. The descriptions of -atime, -ctime, and -mtime use the
terminology n ``86400 second periods (days)''. For example, a
file accessed at 23:59 is selected by:
find . -atime -1 -print
at 00:01 the next day (less than 24 hours later, not more
than one day ago); the midnight boundary between days has no
effect on the 24-hour calculation.
8. The following command:
find . ! -name . -prune -name '*.old' -exec \
sh -c 'mv "$@" ../old/' sh {} +
performs the same task as:
mv ./*.old ./.old ./.*.old ../old/
while avoiding an ``Argument list too long'' error if there
are a large number of files ending with .old and without
running mv if there are no such files (and avoiding ``No such
file or directory'' errors if ./.old does not exist or no
files match ./*.old or ./.*.old).
The alternative:
find . ! -name . -prune -name '*.old' -exec mv {} ../old/ \;
is less efficient if there are many files to move because it
executes one mv command per file.
9. On systems configured to mount removable media on directories
under /media, the following command searches the file
hierarchy for files larger than 100000 KB without searching
any mounted removable media:
find / -path /media -prune -o -size +200000 -print
10. Except for the root directory, and "//" on implementations
where "//" does not refer to the root directory, no pattern
given to -name will match a <slash>, because trailing <slash>
characters are ignored when computing the basename of the
file under evaluation. Given two empty directories named foo
and bar, the following command:
find foo/// bar/// -name foo -o -name 'bar?*'
prints only the line "foo///".
The -a operator was retained as an optional operator for
compatibility with historical shell scripts, even though it is
redundant with expression concatenation.
The descriptions of the '-' modifier on the mode and onum
arguments to the -perm primary agree with historical practice on
BSD and System V implementations. System V and BSD documentation
both describe it in terms of checking additional bits; in fact,
it uses the same bits, but checks for having at least all of the
matching bits set instead of having exactly the matching bits
set.
The exact format of the interactive prompts is unspecified. Only
the general nature of the contents of prompts are specified
because:
* Implementations may desire more descriptive prompts than
those used on historical implementations.
* Since the historical prompt strings do not terminate with
<newline> characters, there is no portable way for another
program to interact with the prompts of this utility via
pipes.
Therefore, an application using this prompting option relies on
the system to provide the most suitable dialog directly with the
user, based on the general guidelines specified.
The -name file operand was changed to use the shell pattern
matching notation so that find is consistent with other utilities
using pattern matching.
The -size operand refers to the size of a file, rather than the
number of blocks it may occupy in the file system. The intent is
that the st_size field defined in the System Interfaces volume of
POSIX.1‐2017 should be used, not the st_blocks found in
historical implementations. There are at least two reasons for
this:
1. In both System V and BSD, find only uses st_size in size
calculations for the operands specified by this volume of
POSIX.1‐2017. (BSD uses st_blocks only when processing the
-ls primary.)
2. Users usually think of file size in terms of bytes, which is
also the unit used by the ls utility for the output from the
-l option. (In both System V and BSD, ls uses st_size for the
-l option size field and uses st_blocks for the ls -s
calculations. This volume of POSIX.1‐2017 does not specify ls
-s.)
The descriptions of -atime, -ctime, and -mtime were changed from
the SVID description of n ``days'' to n being the result of the
integer division of the time difference in seconds by 86400. The
description is also different in terms of the exact timeframe for
the n case (versus the +n or -n), but it matches all known
historical implementations. It refers to one 86400 second period
in the past, not any time from the beginning of that period to
the current time. For example, -atime 2 is true if the file was
accessed any time in the period from 72 hours to 48 hours ago.
Historical implementations do not modify "{}" when it appears as
a substring of an -exec or -ok utility_name or argument string.
There have been numerous user requests for this extension, so
this volume of POSIX.1‐2017 allows the desired behavior. At least
one recent implementation does support this feature, but
encountered several problems in managing memory allocation and
dealing with multiple occurrences of "{}" in a string while it
was being developed, so it is not yet required behavior.
Assuming the presence of -print was added to correct a historical
pitfall that plagues novice users, it is entirely upwards-
compatible from the historical System V find utility. In its
simplest form (find directory), it could be confused with the
historical BSD fast find. The BSD developers agreed that adding
-print as a default expression was the correct decision and have
added the fast find functionality within a new utility called
locate.
Historically, the -L option was implemented using the primary
-follow. The -H and -L options were added for two reasons.
First, they offer a finer granularity of control and consistency
with other programs that walk file hierarchies. Second, the
-follow primary always evaluated to true. As they were
historically really global variables that took effect before the
traversal began, some valid expressions had unexpected results.
An example is the expression -print -o -follow. Because -print
always evaluates to true, the standard order of evaluation
implies that -follow would never be evaluated. This was never the
case. Historical practice for the -follow primary, however, is
not consistent. Some implementations always follow symbolic links
on the command line whether -follow is specified or not. Others
follow symbolic links on the command line only if -follow is
specified. Both behaviors are provided by the -H and -L options,
but scripts using the current -follow primary would be broken if
the -follow option is specified to work either way.
Since the -L option resolves all symbolic links and the -type l
primary is true for symbolic links that still exist after
symbolic links have been resolved, the command:
find -L . -type l
prints a list of symbolic links reachable from the current
directory that do not resolve to accessible files.
A feature of SVR4's find utility was the -exec primary's +
terminator. This allowed filenames containing special characters
(especially <newline> characters) to be grouped together without
the problems that occur if such filenames are piped to xargs.
Other implementations have added other ways to get around this
problem, notably a -print0 primary that wrote filenames with a
null byte terminator. This was considered here, but not adopted.
Using a null terminator meant that any utility that was going to
process find's -print0 output had to add a new option to parse
the null terminators it would now be reading.
The "-exec...{}+" syntax adopted was a result of IEEE PASC
Interpretation 1003.2 #210. It should be noted that this is an
incompatible change to IEEE Std 1003.2‐1992. For example, the
following command printed all files with a '-' after their name
if they are regular files, and a '+' otherwise:
find / -type f -exec echo {} - ';' -o -exec echo {} + ';'
The change invalidates usage like this. Even though the previous
standard stated that this usage would work, in practice many did
not support it and the standard developers felt it better to now
state that this was not allowable.
None.
Section 2.2, Quoting, Section 2.13, Pattern Matching Notation,
Section 2.14, Special Built-In Utilities, chmod(1p), mv(1p),
pax(1p), sh(1p), test(1p)
The Base Definitions volume of POSIX.1‐2017, Chapter 8,
Environment Variables, Section 12.2, Utility Syntax Guidelines
The System Interfaces volume of POSIX.1‐2017, fstatat(3p),
getgrgid(3p), getpwuid(3p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any
discrepancy between this version and the original IEEE and The
Open Group Standard, the original IEEE and The Open Group
Standard is the referee document. The original Standard can be
obtained online at http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 FIND(1P)
Pages that refer to this page: cp(1p), df(1p), diff(1p), ln(1p), ls(1p), test(1p), xargs(1p)
|
HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|