I have a very simple mp3 player, and the order it plays audio files are based on the file names, and the rule is there must be a 3-size number in the beginning of file name, such as:
001file.mp3
002file.mp3
003file.mp3
I want to write a fish shell sortmp3 to add numbers to the files of a directory. Say directory myfiles contains files:
aaa.mp3
bbb.mp3
ccc.mp3`
When I run sortmp3 myfiles, the file names will be changed to:
001aaa.mp3
002bbb.mp3
003ccc.mp3
But my question is:
how to generate some sequential numbers?
how to make sure the size of each number is exactly 3?
I would write this, which makes no assumptions about how many files there are in a directory:
function sortmp3
set -l files *
set -l i
for i in (seq (count $files))
echo mv $files[$i] (printf "%03d%s" $i $files[$i])
end
end
Remove the "echo" if you like how it works.
You can generate sequential numbers with the seq tool - an external program.
This will only take care of the first part, it won't pad to three characters.
To do that, there's a variety of choices:
printf '%s\n' 00(seq 0 99) | rev | cut -c 1-3 | rev
printf '%s\n' 00(seq 0 99) | sed 's/^.*\(...\)$/\1/'
The 00(seq 0 99) part will generate numbers from "1" to "99" with two zeroes prepended - ie. from "001" to "0099". The later parts of the pipeline remove the superfluous zeroes again.
Or with the next fish version, you can use the new string tool:
string sub -s -3 -- 00(seq 0 99)
Depending on your specific situation you should use the "seq" command to generate sequential numbers or the "math" command to increment a counter. To format the number with a predictable number of leading zeros use the "printf" command:
set idx 12
printf '%03d' $idx
Related
as an example I will put different inputs to keep the privacy of my files and to avoid long text, these are of the following form :
INPUT1.cfg :
TC # aa # D317
TC # bb # D314
TC # cc # D315
TC # dd # D316
INPUT2.cfg
BL;nn;3
LY;ww;3
LO;xx;3
TC;vv;3
TC;dd;3
OD;pp;3
TC;aa;3
what I want to do is iterate the name (column 2) in the rows of input1 and compare with the name (column 2) in the rows of input2; if they match we will get the line of INPUT2 in an output file otherwise it will return that the table is not found, here is my try code:
#!/bin/bash
input1="input1.cfg";
input2="input2.cfg"
cat $input1|while read line
do
TableNameIN=`echo $line|cut -d"#" -f2`
cat $input2| while read line
do
TableNameOUT=`echo $line|cut -d";" -f2`
if echo "$TableNameOUT" | grep -q $TableNameIN;
then echo "$line" >> output.txt
else
echo "Table $TableNameIN non trouvé"
fi
done
done
this what i get as result :
Table bb not found
Table bb not found
Table bb not found
Table cc not found
Table cc not found
Table cc not found
I manage to write what is equal but the problem with my code is that it has in output "table not found" for each row whereas I just want to write only once at the end of the comparison of all the lines
here is the output i want to get :
Table bb not found
Table cc not found
Can any one help me with this , PS : I don't want to use awk because it's just a part of my code and i already use sh
Assumptions:
for file input2.cfg the 2nd column (table name) is unique
input2.cfg is not so large that we run the risk of using up all memory for storing intput2.cfg in an associative array (otherwise we could store the table names from input1.cfg's - assuming this is a smaller file - in the array and swap the processing order of the two files)
there are no explicit requirements for data to be sorted (otherwise we may need to add a sort or two)
a bash solution is sufficient (based on inclusion of the #!/bin/bash shebang in OPs current code)
There are many ways to slice-n-dice this one (awk being my preference but OP doesn't want to use awk). For this particular answer I'll pull the awk steps out into separate bash commands.
NOTE: While we could use a set of nested loops (as in the OPs code), I've opted to use an associative array to store input2.cfg thus eliminating the need to repeatedly scan input2.cfg.
#!/usr/bin/bash
input1=input1.cfg
input2=input2.cfg
> output.txt # clear out the target file
# load ${input2} into an associative array
unset lines
typeset -A lines # associative array for storing contents of ${input2}
while read -r line
do
x="${line%;*}" # use parameter expansion
tabname="${x#*;}" # to parse out table name
lines["${tabname}"]="${line}" # add to array
done < "${input2}"
# process ${input1}
while read -r c1 c2 tabname rest_of_line
do
[[ -v lines["${tabname}"] ]] && # if tabname has an entry in our array
echo "${lines[${tabname}]}" >> output.txt && # then dump the associated line (from ${input2}) to output.txt
continue # process next line from ${input1}
echo "Table ${tabname} not found" # otherwise print 'not found' message
done < "${input1}"
# display contents of output.txt
echo "++++++++++++++++ output.txt"
cat output.txt
echo "++++++++++++++++"
This generates the following:
Table bb not found
Table cc not found
++++++++++++++++ output.txt
TC;aa;3
TC;dd;3
++++++++++++++++
I am a beginer in perl and I need to modify a txt file by keeping all the previous data in it and only modify the file by adding 4 to every number related to a specific tag (< COMPRESSED-SIZE >). The file have many lines and tags and looks like below, I need to find all the < COMPRESSED-SIZE > tags and add 4 to the number specified near the tag:
< SOURCE-START-ADDRESS >01< /SOURCE-START-ADDRESS >
< COMPRESSED-SIZE >132219< /COMPRESSED-SIZE >
< UNCOMPRESSED-SIZE >229376< /UNCOMPRESSED-SIZE >
So I guess I need to do something like: search for the keyword(match) and store the number 132219 in a variable and add the second number (4) to it, replace the result 132219 with 132223, the rest of the file must remain unchanged, only the numbers related to this tag must change. I cannot search for the number instead of the tag because the number could change while the tag will remain always the same. I also need to find all the tags with this name and replace the numbers near them by adding 4 to them. I already have the code for finding something after a keyword, because I needed to search also for another tag, but this script does something else, adds a number in front of a keyword. I think I could use this code for what i need, but I do not know how to make the calculation and keep the rest of the file intact or if it is posible in perl.
while (my $row = <$inputFileHandler>)
{
if(index($row,$Data_Pattern) != -1){
my $extract = substr($row, index($row,$Data_Pattern) + length($Data_Pattern), length($row));
my $counter_insert = sprintf "%08d", $counter;
my $spaces = " " x index($row,$Data_Pattern);
$data_to_send ="what i need to add" . $extract;
print {$outs} $spaces . $Data_Pattern . $data_to_send;
$counter = $counter + 1;
}
else
{
print {$outs} $row;
next;
}
}
Maybe you could help me with a block of code for my needs, $Data_Pattern is the match. Thank you very much!
This is a classic one-liner Perl task. Basically you would do something like
$ perl -i.bak -pe's/^< COMPRESSED-SIZE >\K(\d+)/$1 + 4/e' yourfile.txt
Which will in essence copy and replace your file with a new, edited file. This can be very dangerous, especially if you are a Perl newbie. The -i switch is here used with the .bak extension which saves a backup in yourfile.txt.bak. This does not make this operation safe, however, as running the command twice will overwrite the backup.
It is advisable to make a separate backup of the target file before using this command.
-i.bak edit "in-place", the file is overwritten, a backup of the original is created with extension .bak.
-p argument is treated as a file name, which is read, and printed back.
s/ // the substitution operator, which is applied to all lines of the file.
^ inside the regex looks for beginning of line.
\K keep the match that is to the left.
(\d+) capture () 1 or more digits \d+ and store them in $1
/e treat the right hand side of the substitution operator as an expression and use the result as the replacement string. In this case it will increase your number and return the sum.
The long version of this command is
while (<>) {
s/^< COMPRESSED-SIZE >\K(\d+)/$1 + 4/e
}
Which can be placed in a file and run with the -i switch.
I have several (15) files with names : file1.out, file2.out, file3.out, ....,file15.out. I am reading each file and doing some calculation. Here is a sample.
for file in file*.out; do
echo $file
done
But in this way the files are being read in the order file1.out, file10.out.... ,file15.out, file2.out...,file9.out. Is there any way to read these files in an ascending order i.e. file1.out then file2.out and so on.
Since you know the amount of files you have, you can use a for integer loop
for i in $(seq 1 15); do
echo "file$i.out"
done
For full POSIX compliance (seq is not a standard utility), use a while loop and an explicit counter
i=1
while [ "$i" -le 15 ]; do
echo "file$i.out"
i=$((i+1))
done
Rename your files
If you have less than 100 files you can use the following notation
file1.out => file01.out
Change your sort algorithm
i.e. Use ls -v instead of file*.out
for i in `ls -v file*.out`; do
echo $i;
done;
Let's say I have the first column of the following dataset in a file and I want to emulate the flag in the second column so I export only that row tied to a flag = 1 (dataset is pre-sorted by the target column):
1 1
1 0
1 0
2 1
2 0
2 0
I could run awk 'NR==1 {print; next} seen[$1]++ {print}' dataset but would run into a problem for very large files (seen keeps growing). Is there an alternative to handle this without tracking every single unique value of the target column (here column #1)? Thanks.
So you only have the first column? And would like to generate the second? I think a slightly different awk command could work
awk '{if (last==$1) {flag=0} else {last=$1; flag=1}; print $0,flag}' file.txt
Basically you just check if the first field matches the last one you've seen. Since it's sorted, you don't have to keep track of everything you've seen, only the last one to know if the value is different.
Seems like grep would be fine for this:
$ grep " 1" dataset
I would like to randomly pick some lines (e.g.20) from a file and print it into another but I want to have a seed fixed so that I get the same output if input file is the same.
The examples I've found that pick several lines, their output is different everytime
e.g:
perl -e '$f="inputfile";$_=`wc -l $f`;#l=split( );$r=int rand(#l[0]);system("head -n$r $f|tail -20")'> outputfile
And those that talk about fixed seed and pseudo-random are just for printing numbers, not extracting lines from files, or just extract a single line. Is there a command for unix or some code in perl or similar? (sort -R, --random- & shuf didn't work (using Mac OS X 10.5.8)).
You can set the seed via srand(); (for example. srand(5)) to get a fixed seed for rand.