[Glean] Remove Empty File Folder

Published: January 11, 2021 by SingularityKChen (Last updated: January 11, 2021 )

• Categories:
• Glean 44

• Tags:
• Find 1
• Linux 4
• Xargs 1

• Remove Empty File Folder
  • Introduction to find
    • -empty
    • -name pattern
    • -ctime n
    • -size n[cwbkMG]
    • -exec command {}
  • Introduction to xargs
    • -a inputfile
    • -d delim
    • -n max-args
    • -I replace-str
    • -t

Remove Empty File Folder

We can find the empty directories by find command.

find -type d -empty

And the results can be send to the command xargs or the build-in function -exec in find:

find -type d -empty -exec rm -f {}

Or

find -type d -empty | xargs rm -rf

Introduction to find¹

-empty

File is empty and is either a regular file or a directory.

-name pattern

Base of file name (the path with the leading directories removed) matches shell pattern pattern.

-ctime n

File's status was last changed less than, more than or exactly n*24 hours ago. See the comments for -atime to understand how rounding affects the interpretation of file status change times.

-size n[cwbkMG]

File uses less than, more than or exactly n units of space, rounding up. The following suffixes can be used:

• b for 512-byte blocks (this is the default if no suffix is used)
• c for bytes
• w for two-byte words
• k for kibibytes
• M for mebibytes
• G for gibibytes

-exec command {}

This variant of the -exec action runs the specified command on the selected files, but the command line is built by appending each selected file name at the end; the total number of invocations of the command will be much less than the number of matched files. The command line is built in much the same way that xargs builds its command lines.

Introduction to xargs²

xargs is short for eXtended ARGuments.

-a inputfile

Read names from the file inputfile instead of standard input. If you use this option, the standard input stream remains unchanged when commands are run. Otherwise, stdin is redirected from /dev/null.

-d delim

Input file names are terminated by the specified character delim instead of by whitespace, and any quotes and backslash characters are not considered special (every character is taken literally). Disables the logical end of file marker string, which is treated like any other argument.

# echo "nameXnameXnameXname" | xargs -d X

name name name name

-n max-args

Use at most max-args arguments per command line. Fewer than max-args arguments will be used if the size (see the-s option) is exceeded, unless the -x option is given, in which case xargs will exit.

-I replace-str

Replace occurrences of replace-str in the initial arguments with names read from standard input. Also, unquoted blanks do not terminate arguments; instead, the input is split at newlines only. If replace-str is omitted (omitting it is allowed only for -i), it defaults to {} (like for find -exec). Implies -x and -l 1. The -i option is deprecated in favor of the ‘-I’ option.

# cat arg.txt | xargs -I {} ./sk.sh -p {} -l

-p aaa -l
-p bbb -l
-p ccc -l

ls *.jpg | xargs -n1 -I {} cp {} /data/images

-t

Print the command line on the standard error output before executing it.

1. https://man7.org/linux/man-pages/man1/find.1.html ↩

2. https://www.gnu.org/software/findutils/manual/html_node/find_html/xargs-options.html ↩