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CHAPTER 11. FUNNY COMMANDS
allowed to use the forms +nn, which means \a value strictly greater than nn ", and ,nn, which
means \a value strictly less than nn ". This is rather silly in the case of UIDs, but it will turn handy
with other tests.
Another useful option is -type c , which returns true if the le is of type c . The mnemonics for the
possible choices are the same found in ls; so we have b when the le is a block special; c when the
le is character special; d for directories; p for named pipes; l for symbolic links, and s for sockets.
Regular les are indicated with f. A related test is -xtype, which is similar to -type except in the
case of symbolic links. If -follow has not been given, the le pointed at is checked, instead of the
link itself. Completely unrelated is the test -fstype type . In this case, the lesystem type is checked.
I think that the information is got from le /etc/mtab, the one stating the mounting lesystems; I
am certain that types nfs, tmp, msdos and ext2 are recognized.
Tests -inum nn and -links nn check whether the le has inode number nn , or nn links, while
-size nn is true if the le has nn 512-bytes blocks allocated. (well, not precisely: for sparse les
unallocated blocks are counted too). As nowadays the result of ls -s is not always measured in
512-bytes chunks (Linux for example uses 1k as the unit), it is possible to append to nn the character
b, which means to count in butes, or k , to count in kilobytes.
Permission bits are checked through the test -perm mode . If mode has no leading sign, then the
permission bits of the le must exactly match them. A leading , means that all permission bits
must be set, but makes no assumption for the other; a leading + is satised just if any of the bits
are set. Oops! I forgot saying that the mode is written in octal or symbolically, like you use them
in chmod.
Next group of tests is related to the time in which a le has been last used. This comes handy
when a user has lled his space, as usually there are many les he did not use since ages, and whose
meaning he has forgot. The trouble is to locate them, and find is the only hope in sight. -atime
nn is true if the le was last accessed nn days ago, -ctime nn if the le status was last changed nn
days ago { for example, with a chmod { and -mtime nn if the le was last modied nn days ago.
Sometimes you need a more precise timestamp; the test -newer le is satised if the le considered
has been modied later than le . So, you just have to use touch with the desidered date, and you're
done. GNU nd add the tests -anewer and -cnewer which behave similarly; and the tests -amin, -cmin
and -mmin which count time in minutes instead than 24-hours periods.
Last but not the least, the test I use more often. -name pattern is true if the le name exactly
matches pattern , which is more or less the one you would use in a standard ls. Why `more or less'?
Because of course you have to remember that all the parameters are processed by the shell, and
those lovely metacharacters are expanded. So, a test like -name foo* won't return what you want,
and you should either write -name foo or -name "foo*". This is probably one of the most common
mistakes made by careless users, so write it in BIG letters on your screen. Another problem is that,
like with ls, leading dots are not recognized. To cope with this, you can use test -path pattern which
does not worry about dot and slashes when comparing the path of the considered le with pattern .