I want to rename a bunch of dirs from DIR to DIR.OLD. Ideally I would use the following:
find . -maxdepth 1 -type d -name \"*.y\" -mtime +`expr 2 \* 365` -print0 | xargs -0 -r -I file mv file file.old
But the machine I want to execute this on has BusyBox installed and the BusyBox xargs doesn't support the "-I" option.
What are some common alternative methods for collecting an array of files and then executing on them in a shell script?
You can use -exec
and {}
features of the find
command so you don't need any pipes at all:
find -maxdepth 1 -type d -name "*.y" -mtime +`expr 2 \* 365` -exec mv "{}" "{}.old" \;
Also you don't need to specify '.' path - this is default for find
. And you used extra slashes in "*.y"
. Of course if your file names do not really contain quotes.
In fairness it should be noted, that version with while read
loop is the fastest of proposed here. Here are some example measurements:
$ cat measure
#!/bin/sh
case $2 in
1) find "$1" -print0 | xargs -0 -I file echo mv file file.old ;;
2) find "$1" -exec echo mv '{}' '{}.old' \; ;;
3) find "$1" | while read file; do
echo mv "$file" "$file.old"
done;;
esac
$ time ./measure android-ndk-r5c 1 | wc
6225 18675 955493
real 0m6.585s
user 0m18.933s
sys 0m4.476s
$ time ./measure android-ndk-r5c 2 | wc
6225 18675 955493
real 0m6.877s
user 0m18.517s
sys 0m4.788s
$ time ./measure android-ndk-r5c 3 | wc
6225 18675 955493
real 0m0.262s
user 0m0.088s
sys 0m0.236s
I think it's because find
and xargs
invokes additional /bin/sh (actually exec(3)
does it) every time for execute a command, while shell while
loop do not.
Upd: If your busybox version was compiled without -exec
option support for the find
command then the while
loop or xargs
, suggested in the other answers (one, two), is your way.