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.
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.
OPTIONS
The find utility shall conform to the Base Definitions volume of
IEEE Std 1003.1-2001, 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 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 for all symbolic
links not on the command line shall be that of the link itself.
-L Cause the file information and file type evaluated for each
symbolic link to be those of the file referenced by the link,
and not 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.
OPERANDS
The following operands shall be supported:
The path operand is a pathname of a starting point in the directory
hierarchy.
The first argument 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, 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
filename being examined matches pattern using the pattern
matching notation described in Pattern Matching Notation .
-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 IEEE Std 1003.1-2001 (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 IEEE Std 1003.1-2001 (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 IEEE Std 1003.1-2001). 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
process’ file mode creation mask. 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 permission bits exactly match the value of the
octal number onum and only the bits corresponding to the octal
mask 07777 shall be compared. (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 that are also set in the octal mask 07777 are
set.
-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 follows an
argument containing 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 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 only the two characters
"{}" is present, the behavior is unspecified.
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. 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
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.
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
IEEE Std 1003.1-2001, 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 for the processing of affirmative responses
that should be used to affect the format and contents of
diagnostic messages 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
IEEE Std 1003.1-2001, 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, semicolons, opening
parentheses, and closing parentheses are special to the shell and must
be quoted (see 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 IEEE Std 1003.1-2001,
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.
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>s, 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
IEEE Std 1003.1-2001 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
IEEE Std 1003.1-2001. (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
IEEE Std 1003.1-2001 does not specify ls -s.)
The descriptions of -atime, -ctime, and -mtime were changed from the
SVID description of n "days’’ to "24-hour periods". 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 3 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
IEEE Std 1003.1-2001 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>s) 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 the ISO/IEC 9899:1999 standard. For example, the
following command prints 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.
SEE ALSO
Quoting , Pattern Matching Notation , Special Built-In Utilities ,
chmod() , pax , sh , test , the System Interfaces volume of
IEEE Std 1003.1-2001, getgrgid(), getpwuid(), stat()
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 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 .