I'm trying to create a script to count the number of hidden and non-hidden files in a folder where the script is run. However, I run into an issue where I cannot increment variables.
#!/bin/bash
#A simple script to count the number of hidden and non-hidden files in the folder this script is run in
#Variables to store the number of hidden and non-hidden files and folders
#Variables with a 'h' at the end represent hidden items
files=0
fileh=0
#List all files and folders
#Use grep to folder entries beginning with '-', which are files
#Return the 9th word in the string which is the filename
#Read the filename into the variable 'fls'
ls -al | grep ^- | awk '{print $9}' | while read fls
#If the filename begins, with a dot, it is a hidden file
do
if [[ $fls == .* ]]
then
#Therefore increment the number of hidden files by one
let fileh++
else
#Else, increment the number if non-hidden files by one
let files++
fi
done
#Print out the two numbers
echo $files 'non-hidden files'
echo $fileh 'hidden files'
#When I run this script, the output is always zero for both variables
#I don't know why this doesn't work?!
The output of this script is as follows:
jai@L502X~$ ./script.sh
0 non-hidden files
0 hidden files
What happens on the right hand side of a |
happens in a subshell. Changes to variables in a subshell don't propagate back to the parent shell.
Common workaround: don't use a pipe, use Process substitution:
while read fls ; do
...
done < <(ls -al | grep ^- | awk '{print $9}')
If you want to increment a variable using let
, you have to quote your expression, like in
let "i++"
However, I personally prefer to use the double-parentheses syntax, which is
((i++))
# or, if you want a pre-fixed increment
((++i))
Plus, you can use a way shorter syntax for your if
statement, using &&
and ||
:
[[ $fls == .* ]] && ((++fileh)) || ((++files))
引用变量增量
let "fileh++"
Not the answer to the "increment" question, but a much easier script to do what you're trying to do:
files=`find . -type f`
echo "non-hidden files " `echo "$files" | egrep -v "[/]\.[^/]+$" | wc -l`
echo "hidden files " `echo "$files" | egrep "[/]\.[^/]+$" | wc -l`
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