PROLOG top
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
SYNOPSIS top
find [−H|−L] path... [operand_expression...]
DESCRIPTION top
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 top
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 top
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.
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 top
None.
ENVIRONMENT VARIABLES top
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 top
Default.
STDOUT top
The −print primary shall cause the current pathnames to be written to
standard output. The format shall be:
"%s\n", <path>
STDERR top
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 top
None.
EXTENDED DESCRIPTION top
None.
EXIT STATUS top
The following exit values shall be returned:
0 All path operands were traversed successfully.
>0 An error occurred.
CONSEQUENCES OF ERRORS top
Default.
The following sections are informative.
APPLICATION USAGE top
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 top
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 top
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 top
None.
SEE ALSO top
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.1‐2008, Chapter 8, Environment
Variables, Section 12.2, Utility Syntax Guidelines
The System Interfaces volume of POSIX.1‐2008, fstatat(3p),
getgrgid(3p), getpwuid(3p)
COPYRIGHT top
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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.unix.org/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 .
