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PROGRAM:

NAME

find — find files

SYNOPSIS

find [−H|−L] path... [operand_expression...]

DESCRIPTION

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.

OPTIONS

The find utility shall conform to the Base Definitions volume of POSIX.1‐2008, 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.

OPERANDS

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 ('+') or minus-sign ('−')
sign, 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.1‐2008
(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.1‐2008
(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.1‐2008). 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>. 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> 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>, 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> 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>, 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.

STDIN

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.

INPUT FILES

None.

ENVIRONMENT VARIABLES

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.1‐2008, 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.1‐2008, Chapter 8, Environment
Variables.

ASYNCHRONOUS EVENTS

Default.

STDOUT

The −print primary shall cause the current pathnames to be written to standard output. The
format shall be:

"%s\n", <path>

STDERR

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.

OUTPUT FILES

None.

EXTENDED DESCRIPTION

None.

EXIT STATUS

The following exit values shall be returned:

0 All path operands were traversed successfully.

>0 An error occurred.

CONSEQUENCES OF ERRORS

Default.

The following sections are informative.

APPLICATION USAGE

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.1‐2008, applications must not assume that it actually refers to the
traditional sticky bit.

EXAMPLES

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///".

RATIONALE

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.1‐2008 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.1‐2008. (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.1‐2008 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.1‐2008 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.

FUTURE DIRECTIONS

None.

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