Assume there are several files like the following
CLIENT_1.csv
CLIENT_2.csv
CLIENT_3.csv
CLIENT_4.csv
Is there any shell command/awk that we can use to direct the 1,2,3,4 into a variable named "ID"? So that we can do the following
if [ ${ID} != 4 ]
then
blah blah blah
fi
To get the number part for each file:
for file in CLIENT_*.csv ; do
id=${file%.csv} # remove trailing '.csv'
id=${id#CLIENT_} # remove leading 'CLIENT_'
if [ "$id" != 4 ] ; then ... ; fi
done
This is pretty much a repeat of this question.
How to iterate over files in a directory with Bash?
It uses filename wildcarding to iterate through the list. In your case you would use:
for filename in /mydirectory/CLIENT_*.csv; do
#whatever you wanted to do
done
Here is another way to do it where the filename string pattern is a variable.
bash: filenames with wildcards in variables
The file names are stored in the variable file (looking at the accepted answer) after the wildcarding is expanded in the for loop initialization. Again using the power of wildcarding your example would look something like this:
putfile=CLIENT_*.csv
for file in $putfile; do #whatever you wanted to do
done
Related
I am writing a bash script to loop through all the directories and rename the directory to the value of the array, but it seems my (i th) value is not incrementing correctly and it also says "(i th) command not found" when I run my bash script.
Here is my code: I replaced the values inside Unix with place holder values.
#!/bin/bash
declare -a Unix=(value1 value2 value3 .... );
i = 0
for d in */; do
echo ${Unix[$i]}
#mv $d ${Unix[$i]}
(($i+1))
done
You are doing two things wrong. Firstly , to answer your problem,
(($i+1))
should be
(($i+=1))
also, you should remove the spaces in the line
i = 0
so it looks like
i=0
Firstly, you might want to quote your directory names in the mv command, or you get into trouble with names containing spaces:
mv "$d" "${Unix[i]}"
As you see, it's not necessary to prepend the i in the index with $, as [] is an "arithmetic context" here and expands variable names.
Secondly, your increment does nothing: you just add 1 to i and throw the result away. You can use the increment operator instead:
(( ++i ))
Again, the $ is not needed.
Would like to read multiple values from a property file using a shell script
My properties files looks something like below, the reason I added it following way was to make sure, if in future more students joins I just need to add in in the properties file without changing any thing in the shell script.
student.properties
total_student=6
student_name_1="aaaa"
student_name_2="bbbb"
student_name_3="cccc"
student_name_4="dddd"
student_name_5="eeee"
When I run below script I not getting the desired output, for reading the student names from properties file
student.sh
#!/bin/bash
. /student.properties
i=1
while [ $i -lt $total_student ]
do
{
std_Name=$student_name_$i
echo $std_Name
#****** my logic *******
} || {
echo "ERROR..."
}
i=`expr $i + 1`
done
Output is something like this
1
2
3
4
5
I understand the script is not getting anything for $student_name_ hence only $i value is getting printed.
Hence, wanted to know how to read values from the properties file.
You can do variable name interpolation with ${!foo}. If $foo is "bar", then ${!foo} gives you the value of $bar. In your code that means changing
std_Name=$student_name_$i
to
var=student_name_$i
std_Name=${!var}
Alternatively, you could store the names in an array. Then you wouldn't have to do any parsing.
student.properties
student_names=("aaaa" "bbbb" "cccc" "dddd" "eeee")
student.sh
#!/bin/bash
. /student.properties
for student_name in "${student_names[#]}"; do
...
done
You can use indirect expansion:
std_Name=student_name_$i
echo "${!std_Name}"
the expression ${!var} basically evaluates the variable twice:
first evaluation: student_name_1
second evaluation: foo
Note that this is rarely a good idea and that using an array is almost always preferred.
I want to run a shell script that can simultaneously loop through two variables.
So that I can have an input and output file name. I feel like this isn't too hard of a concept but any help is appreciated.
Files = "File1,
File2,
...
FileN
"
Output = OutFile1,
Outfile2,
...
OutfileN
"
and I would in theory my code would be:
for File in $Files
do
COMMAND --file $File --ouput $Output
done
Obviously, there needs to be another loop but I'm stuck, any help is appreciated.
You don't really need to loop 2 variables, just use 2 BASH arrays:
input=("File1" "File2" "File3")
output=("OutFile1" "OutFile2" "OutFile3")
for ((i=0; i<${#input[#]}; i++)); do
echo "Processing input=${input[$i]} and output=${output[$i]}"
done
zsh enables multiple loop variables before the list.
#!/bin/zsh
input2output=(
'File1' 'Outfile1'
'File2' 'Outfile2'
)
for input ouput in $input2output
do
echo "[$input] --> [$ouput]"
done
quotes from zsh(5.9) manual or man zshmisc
for name ... [ in word ... ] term do list done
More than one parameter name can appear before the list of words. If N names are given, then on each execution of the loop the next N words are assigned to the corresponding parameters. If there are more names than remaining words, the remaining parameters are each set to the empty string.
I know how to parse a string into variables in the manner of this SO question, e.g.
ABCDE-123456
becomes:
var1=ABCDE
var2=123456
via, say, cut. I can do that in one script, no problem.
But I have a few dozen scripts which parse strings/arguments all in the same fashion (same arguments & variables, i.e. same parsing strategy).
And sometimes I need to make a change or add a variable to the parsing mechanism.
Of course, I could go through every one of my dozens of scripts and change the parsing manually (even if just copy & paste), but that would be tedious and more error-prone to bugs/mistakes.
Is there a modular way to do parse strings/arguments as such?
I thought of writing a script which parses the string/args into variables and then exports, but the export command does not work form child-to-parent, (only vice-versa).
Something like this might work:
parse_it () {
SEP=${SEP--}
string=$1
names=${#:2}
IFS="$SEP" read $names <<< "$string"
}
$ parse_it ABCDE-123456 var1 var2
$ echo "$var1"
ABCDE
$ echo "$var2"
123456
$ SEP=: parse_it "foo:bar:baz" id1 id2 id3
$ echo $id2
bar
The first argument is the string to parse, the remaining arguments are names of variables that get passed to read as the variables to set. (Not quoting $names here is intentional, as we will let the shell split the string into multiple words, one per variable. Valid variable names consist of only _, letters, and numbers, so there are no worries about undesired word splitting or pathname generation by not quoting $names). The function assumes the string uses a single separator of "-", which can be overridden via the environment.
For more complex parsing, you may want to use a custom regular expression (bash 4 or later required for the -g flag to declare):
parse_it () {
reg_ex=$1
string=$2
shift 2
[[ $string =~ $reg_ex ]] || return
i=1
for name; do
declare -g "$name=${BASH_REMATCH[i++]}"
done
}
$ parse_it '(.*)-(.*):(.*)' "abc-123:xyz" id1 id2 id3
$ echo "$id2"
123
I think what you really want is to write your function in one script and include it in all of your other scripts.
You can include other shell scripts by the source or . command.
For example, you can define your parse function in parseString.sh
function parseString {
...
}
And then in any of your other script, do
source parseString.sh
# now we can call parseString function
parseString abcde-12345
There are several posts about iterating through bash files like this:
count_files() {
count=0
for f in "filename_*.txt"
do
count=$(($count + 1))
done
echo "Current count:$count"
}
I need to pass in "filename_*.txt" as a param when calling the bash script. Like this:
$: count_files.sh "filename_*.txt"
$: count_files.sh "different_filename_*.txt"
This, however, only gets the first file:
count_files() {
count=0
for f in $1
do
count=$(($count + 1))
done
echo "Current count:$count"
}
How do I pass in a regex param and iterate through it?
NOTE: counting the files is just an example. If you have a simple way to do that, please share, but that's not the main question.
Inside count_files.sh script make sure you call function with quotes like this:
count_files "$1"
instead of:
count_files $1
Later will get you count=1 because wildcard will be expanded before function call to the first file name.