You can test for file attributes that none of the find builtin
tests check. To do this, use xargs to run a program that filters
a list of files printed by find. If possible, use find
builtin tests to pare down the list, so the program run by xargs
has less work to do. The tests builtin to find will likely run
faster than tests that other programs perform.
For example, here is a way to print the names of all of the unstripped
binaries in the `/usr/local' directory tree. Builtin tests avoid
running file on files that are not regular files or are not
executable.
find /usr/local -type f -perm +a=x | xargs file | grep 'not stripped' | cut -d: -f1
The cut program removes everything after the file name from the
output of file.
If you want to place a special test somewhere in the middle of a
find expression, you can use `-exec' to run a program that
performs the test. Because `-exec' evaluates to the exit status of
the executed program, you can write a program (which can be a shell
script) that tests for a special attribute and make it exit with a true
(zero) or false (non-zero) status. It is a good idea to place such a
special test after the builtin tests, because it starts a new
process which could be avoided if a builtin test evaluates to false.
Use this method only when xargs is not flexible enough, because
starting one or more new processes to test each file is slower than
using xargs to start one process that tests many files.
Here is a shell script called unstripped that checks whether its
argument is an unstripped binary file:
#!/bin/sh file $1 | grep 'not stripped' > /dev/null
This script relies on the fact that the shell exits with the status of
the last program it executed, in this case grep. grep
exits with a true status if it found any matches, false if not. Here is
an example of using the script (assuming it is in your search path). It
lists the stripped executables in the file `sbins' and the
unstripped ones in `ubins'.
find /usr/local -type f -perm +a=x \
\( -exec unstripped '{}' \; -fprint ubins -o -fprint sbins \)
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