Bash Journey
Table of contents
Disk usage per directory
$ du -hs */
52K dist/
5.5M docs/
417K htmlcov/
124K src/
25K tests/
To sort the output pipe the result to the sort command:
$ du -hs */ | sort -hr
5.5M docs/
417K htmlcov/
124K src/
52K dist/
25K tests/
Disk usage (du) command related help:
Usage: du [OPTION]... [FILE]...
or: du [OPTION]... --files0-from=F
Summarize disk usage of the set of FILEs, recursively for directories.
Mandatory arguments to long options are mandatory for short options too.
...
-h, --human-readable print sizes in human readable format (e.g., 1K 234M 2G)
...
-s, --summarize display only a total for each argument
...
Disk usage (du) command full help:
Usage: du [OPTION]... [FILE]...
or: du [OPTION]... --files0-from=F
Summarize disk usage of the set of FILEs, recursively for directories.
Mandatory arguments to long options are mandatory for short options too.
-0, --null end each output line with NUL, not newline
-a, --all write counts for all files, not just directories
--apparent-size print apparent sizes, rather than disk usage; although
the apparent size is usually smaller, it may be
larger due to holes in ('sparse') files, internal
fragmentation, indirect blocks, and the like
-B, --block-size=SIZE scale sizes by SIZE before printing them; e.g.,
'-BM' prints sizes in units of 1,048,576 bytes;
see SIZE format below
-b, --bytes equivalent to '--apparent-size --block-size=1'
-c, --total produce a grand total
-D, --dereference-args dereference only symlinks that are listed on the
command line
-d, --max-depth=N print the total for a directory (or file, with --all)
only if it is N or fewer levels below the command
line argument; --max-depth=0 is the same as
--summarize
--files0-from=F summarize disk usage of the
NUL-terminated file names specified in file F;
if F is -, then read names from standard input
-H equivalent to --dereference-args (-D)
-h, --human-readable print sizes in human readable format (e.g., 1K 234M 2G)
--inodes list inode usage information instead of block usage
-k like --block-size=1K
-L, --dereference dereference all symbolic links
-l, --count-links count sizes many times if hard linked
-m like --block-size=1M
-P, --no-dereference don't follow any symbolic links (this is the default)
-S, --separate-dirs for directories do not include size of subdirectories
--si like -h, but use powers of 1000 not 1024
-s, --summarize display only a total for each argument
-t, --threshold=SIZE exclude entries smaller than SIZE if positive,
or entries greater than SIZE if negative
--time show time of the last modification of any file in the
directory, or any of its subdirectories
--time=WORD show time as WORD instead of modification time:
atime, access, use, ctime or status
--time-style=STYLE show times using STYLE, which can be:
full-iso, long-iso, iso, or +FORMAT;
FORMAT is interpreted like in 'date'
-X, --exclude-from=FILE exclude files that match any pattern in FILE
--exclude=PATTERN exclude files that match PATTERN
-x, --one-file-system skip directories on different file systems
--help display this help and exit
--version output version information and exit
Display values are in units of the first available SIZE from --block-size,
and the DU_BLOCK_SIZE, BLOCK_SIZE and BLOCKSIZE environment variables.
Otherwise, units default to 1024 bytes (or 512 if POSIXLY_CORRECT is set).
The SIZE argument is an integer and optional unit (example: 10K is 10*1024).
Units are K,M,G,T,P,E,Z,Y (powers of 1024) or KB,MB,... (powers of 1000).
Binary prefixes can be used, too: KiB=K, MiB=M, and so on.
GNU coreutils online help: <https://www.gnu.org/software/coreutils/>
Full documentation <https://www.gnu.org/software/coreutils/du>
or available locally via: info '(coreutils) du invocation'
Execute command multiple times with xargs
Let’s start with simple example. We want to create directories named test-one,
test-two and test-three. We can do it by running the mkdir command multiple times:
$ mkdir test-one
$ mkdir test-two
$ mkdir test-three
You could achieve the same by using the xargs command:
$ echo $'test-one\ntest-two\ntest-three' | xargs mkdir
The echo command prints three lines to the output:
test-one
test-two
test-three
The output is sent (piped) to the xargs command’s standard input. For each line from the
input the xargs command executes the specified mkdir command, passing the content of
the line as to mkdir.
This has the same effect as running the mkdir command three times as we did eariler.
To clean up we could do the same, but this time we use the rm command to remove the directories
we created.
echo $'test-one\ntest-two\ntest-three' | xargs rm -r
xargs has a lot of options which could be used to modify it’s behavior. Here are just some of them:
$ echo -n 'one two three' | xargs -I % -t -d ' ' echo say %
echo say one
say one
echo say two
say two
echo say three
say three
-I %option changes the argument placeholder to%-toption instructs xargs to print the command before executing-d ' 'option changes the argument separator from the standard inputecho say %is the command whichxargswill execute for each argument from the input.%denotes a placeholder wherexargsplaces the actual argument value.
Here is the full output of the xargs help:
Usage: xargs [OPTION]... COMMAND [INITIAL-ARGS]...
Run COMMAND with arguments INITIAL-ARGS and more arguments read from input.
Mandatory and optional arguments to long options are also
mandatory or optional for the corresponding short option.
-0, --null items are separated by a null, not whitespace;
disables quote and backslash processing and
logical EOF processing
-a, --arg-file=FILE read arguments from FILE, not standard input
-d, --delimiter=CHARACTER items in input stream are separated by CHARACTER,
not by whitespace; disables quote and backslash
processing and logical EOF processing
-E END set logical EOF string; if END occurs as a line
of input, the rest of the input is ignored
(ignored if -0 or -d was specified)
-e, --eof[=END] equivalent to -E END if END is specified;
otherwise, there is no end-of-file string
-I R same as --replace=R
-i, --replace[=R] replace R in INITIAL-ARGS with names read
from standard input; if R is unspecified,
assume {}
-L, --max-lines=MAX-LINES use at most MAX-LINES non-blank input lines per
command line
-l[MAX-LINES] similar to -L but defaults to at most one non-
blank input line if MAX-LINES is not specified
-n, --max-args=MAX-ARGS use at most MAX-ARGS arguments per command line
-o, --open-tty Reopen stdin as /dev/tty in the child process
before executing the command; useful to run an
interactive application.
-P, --max-procs=MAX-PROCS run at most MAX-PROCS processes at a time
-p, --interactive prompt before running commands
--process-slot-var=VAR set environment variable VAR in child processes
-r, --no-run-if-empty if there are no arguments, then do not run COMMAND;
if this option is not given, COMMAND will be
run at least once
-s, --max-chars=MAX-CHARS limit length of command line to MAX-CHARS
--show-limits show limits on command-line length
-t, --verbose print commands before executing them
-x, --exit exit if the size (see -s) is exceeded
--help display this help and exit
--version output version information and exit
Please see also the documentation at http://www.gnu.org/software/findutils/.
You can report (and track progress on fixing) bugs in the "xargs"
program via the GNU findutils bug-reporting page at
https://savannah.gnu.org/bugs/?group=findutils or, if
you have no web access, by sending email to <bug-findutils@gnu.org>.
Here are some typical uses of the xargs command:
$ # Remove files older than two weeks
$ find /tmp -mtime +14 | xargs rm
$ # Same but using the find's -exec option. Notice the \; at the end
$ find /tmp -mtime +14 -exec rm {} \;
$ # Prompt before executing the each command
$ find /tmp -mtime +14 | xargs -p rm