给定files.txt中的文件列表，我可以得到它们的大小列表，如下所示:
cat files.txt | xargs ls -l | cut -c 23-30
这会产生这样的结果:
151552
319488
1536000
225280
我怎样才能得到所有这些数字的总数呢?
当前回答
... |xargs|tr \ +|bc
... |paste -sd+ -|bc
第一个命令只是多了一个符号(注意，它必须在反斜杠后面有两个空格!)，但它处理列中有空行的情况，而第二个命令导致带有额外加号的无效表达式。
例如:
echo "2
3
5
" | paste -sd+ -
结果
2+3+5++
哪个BC不能处理，而
echo "2
3
5
" | xargs | tr \ +
给出一个有效表达式
2+3+5
哪些可以被导入BC以获得最终结果
其他回答
#
# @(#) addup.sh 1.0 90/07/19
#
# Copyright (C) <heh> SjB, 1990
# Adds up a column (default=last) of numbers in a file.
# 95/05/16 updated to allow (999) negative style numbers.
case $1 in
-[0-9])
COLUMN=`echo $1 | tr -d -`
shift
;;
*)
COLUMN="NF"
;;
esac
echo "Adding up column .. $COLUMN .. of file(s) .. $*"
nawk ' OFMT="%.2f" # 1 "%12.2f"
{ x = '$COLUMN' # 2
neg = index($x, "$") # 3
if (neg > 0) X = gsub("\\$", "", $x)
neg = index($x, ",") # 4
if (neg > 1) X = gsub(",", "", $x)
neg = index($x, "(") # 8 neg (123 & change
if (neg > 0) X = gsub("\\(", "", $x)
if (neg > 0) $x = (-1 * $x) # it to "-123.00"
neg = index($x, "-") # 5
if (neg > 1) $x = (-1 * $x) # 6
t += $x # 7
print "x is <<<", $x+0, ">>> running balance:", t
} ' $*
# 1. set numeric format to eliminate rounding errors
# 1.1 had to reset numeric format from 12.2f to .2f 95/05/16
# when a computed number is assigned to a variable ( $x = (-1 * $x) )
# it causes $x to use the OFMT so -1.23 = "________-1.23" vs "-1.23"
# and that causes my #5 (negative check) to not work correctly because
# the index returns a number >1 and to the neg neg than becomes a positive
# this only occurs if the number happened to b a "(" neg number
# 2. find the field we want to add up (comes from the shell or defaults
# to the last field "NF") in the file
# 3. check for a dollar sign ($) in the number - if there get rid of it
# so we may add it correctly - $12 $1$2 $1$2$ $$1$$2$$ all = 12
# 4. check for a comma (,) in the number - if there get rid of it so we
# may add it correctly - 1,2 12, 1,,2 1,,2,, all = 12 (,12=0)
# 5. check for negative numbers
# 6. if x is a negative number in the form 999- "make" it a recognized
# number like -999 - if x is a negative number like -999 already
# the test fails (y is not >1) and this "true" negative is not made
# positive
# 7. accumulate the total
# 8. if x is a negative number in the form (999) "make it a recognized
# number like -999
# * Note that a (-9) (neg neg number) returns a postive
# * Mite not work rite with all forms of all numbers using $-,+. etc. *
我会用“du”来代替。
$ cat files.txt | xargs du -c | tail -1
4480 total
如果你只想要数字:
cat files.txt | xargs du -c | tail -1 | awk '{print $1}'
在我看来，最简单的解决方案是"expr" unix命令:
s=0;
for i in `cat files.txt | xargs ls -l | cut -c 23-30`
do
s=`expr $s + $i`
done
echo $s
如果你只想使用shell脚本而不使用awk或其他解释器，你可以使用下面的脚本:
#!/bin/bash
total=0
for number in `cat files.txt | xargs ls -l | cut -c 23-30`; do
let total=$total+$number
done
echo $total
粘贴不是必需的。只要files.txt包含一个或多个有效文件名，就可以执行以下操作:
<files.txt xargs stat -c %s | paste -sd+ | bc
如果没有文件，Cat不需要插入0。如果没有管道，也许在脚本中更方便，您可以使用:
(xargs -a files.txt stat -c %s || echo 0) | paste -sd+ | bc
