-exec COMMAND \;
Carries out COMMAND on
each file that find matches.
The command sequence terminates with \;
(the ";" is escaped to make certain
the shell passes it to find
literally). If COMMAND
contains {}, then find
substitutes the full path name of the selected file for
"{}".
bash$ find ~/ -name '*.txt'
/home/bozo/.kde/share/apps/karm/karmdata.txt
/home/bozo/misc/irmeyc.txt
/home/bozo/test-scripts/1.txt
|
find /home/bozo/projects -mtime 1
# Lists all files in /home/bozo/projects directory tree
#+ that were modified within the last day.
#
# mtime = last modification time of the target file
# ctime = last status change time (via 'chmod' or otherwise)
# atime = last access time
DIR=/home/bozo/junk_files
find "$DIR" -type f -atime +5 -exec rm {} \;
# Deletes all files in "/home/bozo/junk_files"
#+ that have not been accessed in at least 5 days.
#
# "-type filetype", where
# f = regular file
# d = directory, etc.
# (The 'find' manpage has a complete listing.) |
find /etc -exec grep '[0-9][0-9]*[.][0-9][0-9]*[.][0-9][0-9]*[.][0-9][0-9]*' {} \;
# Finds all IP addresses (xxx.xxx.xxx.xxx) in /etc directory files.
# There a few extraneous hits - how can they be filtered out?
# Perhaps by:
find /etc -type f -exec cat '{}' \; | tr -c '.[:digit:]' '\n' \
| grep '^[^.][^.]*\.[^.][^.]*\.[^.][^.]*\.[^.][^.]*$'
# [:digit:] is one of the character classes
# introduced with the POSIX 1003.2 standard.
# Thanks, S.C. |
 | The -exec option to
find should not be confused with the exec shell builtin. |
Example 12-2. Badname, eliminate file names
in current directory containing bad characters and whitespace.
#!/bin/bash
# Delete filenames in current directory containing bad characters.
for filename in *
do
badname=`echo "$filename" | sed -n /[\+\{\;\"\\\=\?~\(\)\<\>\&\*\|\$]/p`
# Files containing those nasties: + { ; " \ = ? ~ ( ) < > & * | $
rm $badname 2>/dev/null # So error messages deep-sixed.
done
# Now, take care of files containing all manner of whitespace.
find . -name "* *" -exec rm -f {} \;
# The path name of the file that "find" finds replaces the "{}".
# The '\' ensures that the ';' is interpreted literally, as end of command.
exit 0
#---------------------------------------------------------------------
# Commands below this line will not execute because of "exit" command.
# An alternative to the above script:
find . -name '*[+{;"\\=?~()<>&*|$ ]*' -exec rm -f '{}' \;
exit 0
# (Thanks, S.C.) |
Example 12-3. Deleting a file by its inode
number
#!/bin/bash
# idelete.sh: Deleting a file by its inode number.
# This is useful when a filename starts with an illegal character,
#+ such as ? or -.
ARGCOUNT=1 # Filename arg must be passed to script.
E_WRONGARGS=70
E_FILE_NOT_EXIST=71
E_CHANGED_MIND=72
if [ $# -ne "$ARGCOUNT" ]
then
echo "Usage: `basename $0` filename"
exit $E_WRONGARGS
fi
if [ ! -e "$1" ]
then
echo "File \""$1"\" does not exist."
exit $E_FILE_NOT_EXIST
fi
inum=`ls -i | grep "$1" | awk '{print $1}'`
# inum = inode (index node) number of file
# Every file has an inode, a record that hold its physical address info.
echo; echo -n "Are you absolutely sure you want to delete \"$1\" (y/n)? "
# The '-v' option to 'rm' also asks this.
read answer
case "$answer" in
[nN]) echo "Changed your mind, huh?"
exit $E_CHANGED_MIND
;;
*) echo "Deleting file \"$1\".";;
esac
find . -inum $inum -exec rm {} \;
echo "File "\"$1"\" deleted!"
exit 0 |
See Example 12-22, Example 3-4,
and Example 10-9 for scripts using
find. Its manpage provides more detail
on this complex and powerful command.
A filter for feeding arguments to a command, and also
a tool for assembling the commands themselves. It breaks
a data stream into small enough chunks for filters
and commands to process. Consider it as a powerful
replacement for backquotes. In situations where backquotes
fail with a too many arguments
error, substituting xargs often
works. Normally, xargs reads from
stdin or from a pipe, but it can also
be given the output of a file.
The default command for xargs is
echo. This means that input
piped to xargs may have linefeeds and
other whitespace characters stripped out.
bash$ ls -l
total 0
-rw-rw-r-- 1 bozo bozo 0 Jan 29 23:58 file1
-rw-rw-r-- 1 bozo bozo 0 Jan 29 23:58 file2
bash$ ls -l | xargs
total 0 -rw-rw-r-- 1 bozo bozo 0 Jan 29 23:58 file1 -rw-rw-r-- 1 bozo bozo 0 Jan 29 23:58 file2
|
ls | xargs -p -l gzip gzips every file in current
directory, one at a time, prompting before each
operation.
 | An interesting xargs
option is -n NN,
which limits to NN the number
of arguments passed. ls | xargs -n 8 echo lists the files in the
current directory in 8 columns. |
| Another useful option is
-0, in combination with find
-print0 or grep -lZ. This
allows handling arguments containing whitespace or
quotes. find / -type f -print0 | xargs -0 grep -liwZ GUI | xargs -0 rm -f
grep -rliwZ GUI / | xargs -0 rm -f
Either of the above will remove any file containing "GUI".
(Thanks, S.C.) |
Example 12-4. Logfile using xargs to monitor system log
#!/bin/bash
# Generates a log file in current directory
# from the tail end of /var/log/messages.
# Note: /var/log/messages must be world readable
# if this script invoked by an ordinary user.
# #root chmod 644 /var/log/messages
LINES=5
( date; uname -a ) >>logfile
# Time and machine name
echo --------------------------------------------------------------------- >>logfile
tail -$LINES /var/log/messages | xargs | fmt -s >>logfile
echo >>logfile
echo >>logfile
exit 0
# Exercise:
# --------
# Modify this script to track changes in /var/log/messages at intervals
#+ of 20 minutes.
# Hint: Use the "watch" command. |
Example 12-5. copydir, copying files in current
directory to another, using xargs
#!/bin/bash
# Copy (verbose) all files in current directory
# to directory specified on command line.
if [ -z "$1" ] # Exit if no argument given.
then
echo "Usage: `basename $0` directory-to-copy-to"
exit 65
fi
ls . | xargs -i -t cp ./{} $1
# This is the exact equivalent of
# cp * $1
# unless any of the filenames has "whitespace" characters.
exit 0 |
