Contents:
The find Command Is Great; The Problem Is Finding How to Use It
Delving Through a Deep Directory Tree
Don't Forget -print
Looking for Files with Particular Names
Searching for Old Files
Be an Expert on find Search Operators
The Times that find Finds
Exact File Time Comparisons
Problems with -newer
Running Commands on What You Find
Using -exec to Create Custom Tests
Finding Many Things with One Command
Searching for Files by Type
Searching for Files by Size
Searching for Files by Permission
Searching by Owner and Group
Duplicating a Directory Tree (No Pathnames with find {} Operator)
Using "Fast find"
Finding Files (Much) Faster with a find Database
grepping a Directory Tree (and a Gotcha)
lookfor: Which File Has that Word?
Finding the Links to a File
Finding Files with -prune
Skipping Some Parts of a Tree in find (A More Selective -prune)
Keeping find From Searching Networked Filesystems
find is one of UNIX's most useful and important utilities. It finds files that match a given set of parameters, ranging from the file's name to its modification date. In this chapter, we'll be looking at many of the things it can do. As an introduction, here's a quick summary of its features and operators:
%find
path operators
where path
is the directory in which find will begin to
search and operators
(or, in more customary jargon,
options) tell find which files you're interested in. The
operators
are:
-name
filename
Find files with the given filename
. This
is the most commonly used operator. filename
may include
wildcards (15.2),
but if it does, it must be quoted to prevent the shell
from interpreting the wildcards.
See article
17.4.
-perm
mode
Find files with the given
access mode
(22.2).
You must give the access mode in
octal (1.23).
See articles
17.10
and
17.15.
-type
c
The files of the given type, specified by c
.
c
is a one-digit code; for example, f
for a plain file,
b
for a block special file, l
for a symbolic link, etc.
See article
17.13.
-user
name
Find files belonging to user name
.
name
may also be a
user ID number (38.3).
See article
17.16.
-group
name
Find files belonging to group name
.
name
may also be a
group ID number (38.3).
See article
17.16.
-size
n
Find files that are n
blocks long. A block
equals 512 bytes. The notation +
n
says "find files that are
over n
blocks long." The notation n
c
says "find files
that are n
characters long." Can you guess what +
n
c
means?
See article
17.14.
-inum
n
Find files with the
inode number (1.22)
n
.
See article
17.10.
-atime
n
Find files that were accessed n
days ago.
+
n
means "find files that were accessed over n days ago"
(i.e., not accessed in the last n days).
-
n
means "find files that were accessed less than n days ago"
(i.e., accessed in the last n days).
See articles
17.5
and
17.7.
-mtime
n
Similar to atime, except that it checks the time the file's contents were modified. See articles 17.5 and 17.7.
-ctime
n
Similar to atime, except that it checks the time the inode (1.22) was last changed. "Changed" means that the file was modified or that one of its attributes (for example, its owner) was changed. See articles 17.5 and 17.7.
-newer
file
Find files that have been modified more
recently than the given file
.
See articles
17.8
and
17.9.
Of course, you often want to take some action on files that match several criteria. So we need some way to combine several operators:
operator1
-a
operator2
Find files that match both operator1
and operator2
. The -a
isn't necessary; when two search
parameters are juxtaposed, find assumes you want files that
match both of them.
See article
17.12.
operator1
-o
operator2
Find files that match either
operator1
or operator2
.
See article
17.6.
!
operator
Find all files that do not match the given
operator
. The !
performs a logical NOT operation.
See article
17.6.
\(
expression
\)
Logical precedence; in a complex
expression, evaluate this part of the expression
before the rest.
See article
17.6.
Another group of operators tells find what action to take when it locates a file:
-print
Print the file's name on standard output. See articles 17.2 and 17.3.
-exec
command
Execute command
. To include the
pathname of the file that's just been found in command
, use the
special symbol {}
. command
must end with a backslash
followed by a semicolon (\;
). For example:
%find -name "*.o" -exec rm -f {} \;
tells find to delete any files whose names end in .o. See article 17.10.
-ok
command
Same as -exec, except that find
prompts you for permission before executing command
. This is a
useful way to test find commands.
See article
17.10.
A last word: find is one of the tools that vendors frequently fiddle with, adding (or deleting) a few operators that they like (or dislike). The operators listed above should be valid on virtually any system. If you check your system's manual page, you may find a few others.
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