Hello all I hope someone can help me. I am trying to convert something I wrote in C to bash.
But how do I go about reading more than one item at a time in a for loop?
i have been using this format for the loops in the bash script i have been building.
e.g.
Code:
for word in `cat -s sortlist2.txt`
do
echo -e "$word\n";
done
but now i need more than one variable per pass of the loop.
here is the format of the sortlist2.txt. it is the path/name and time-stamp space separated one entry per line:
The C code reads in the data and keeps the first unique entry (saved to sortlist3.txt) and puts the repeat time-stamp entries in a file (rmlist.txt) for removing those player files later.
here is the C code:
Code:
if ((fpr = fopen("../../../parchive/rmlist.txt", "w")) == NULL)
{
perror("couldn't open rmlist.txt for writing.");
return;
}
if ((fp = fopen("../../../parchive/sortlist2.txt", "r")) != NULL)
{
name = fread_word(fp);
logo = fread_number(fp);
if ((fpo = fopen("../../../parchive/sortlist3.txt", "w")) != NULL)
{
fprintf(fpo, "%s %ld\n", name, logo);
for (;;)
{
prev_name = name;
prev_logo = logo;
name = fread_word(fp);
if (name[0] == '$')
{
fprintf(fpo, "$\n");
break;
}
logo = fread_number(fp);
if (logo == prev_logo)
{
fprintf(fpr, "%s\n", name);
continue;
}
fprintf(fpo, "%s %ld\n", name, logo);
}
}
else
{
perror("couldn't open sortlist3.txt for writing.");
}
fclose(fp);
fclose(fpo);
fclose(fpr);
}
or is there some slick bash command(s) that can do this sorting?
I can get rid of the $ at the end of the file if needed. I just needed it for C to detect the end of the list. I thought about reading the file into two arrays, $name[] and $logo[] and then do the filtering. Possibly use the read command and a while statement? Thanks.
But how do I go about reading more than one item at a time in a for loop?
First off, you shouldn't use for-loops for that purpose at all. A for-loop loops through a list of values and as soon as this list gets longer than the maximum line length the shell can handle (as per POSIX 4096 characters are guaranteed) the command will break.
The shell evaluates first what you have written in backticks and replaces the command with its output, basically putting the whole content of the file on the command line. Only then the for-loop is executed.
Use a while-loop for that purpose so you do not run the risk of the commandline getting too long with the added benefit of being able to cycle any number of variables instead of only one:
Code:
cat /path/to/file | while read valueA valueB ; do
echo Value1 = ${valueA} \tValue2 = ${valueB}
done
Some might say that it would be possible to save the one pipeline by writing the feeding file at the end of the loop:
Code:
while read valueA valueB ; do
echo Value1 = ${valueA} \tValue2 = ${valueB}
done < /path/to/file
While this is syntactically correct IMHO the first version is easier to read and to maintain, which is why i prefer to do it this way.
Could you please share you required output sample data with input file...
so that makes clear picture...
Thanks
Sha
ok thanks to everyone so far; bakunin for the loop/read help, and hard aix; using your examples made me realize I have an error in my C code.
a contingency I did not realize was a possibility, filtering stuff that should not be filtered. the orig sortlist2.txt file has 14655 entries to sort through so it is a long file.
Here is a different section from the sortlist2.txt file:
So from a C standpoint i would need to, if the previous logout is the same as the one currently being read, then isolate the name from the directory and compare names also.
so from bash i would need to replace the / with a space to create 3 arguments per line, do the comparisons. but keep the / in the outputted lists.
and finally here is how the sortlis2.txt is being generated:
Code:
#!/bin/bash
rm blahlist.txt;
for adirfile in `cat -s adir.lst`
do
echo -e "\e[0m adding list from \e[31m $adirfile \e[36m\n\n";
grep -m 1 LogO $adirfile/* >> blahlist.txt;
done
echo -e "sorting list...\n\r";
sort -g -k 2 blahlist.txt > sortlist.txt;
echo -e "removing grep data...\n\r";
sed 's/:LogO//' sortlist.txt > sortlist2.txt;
echo "$" >> sortlist2.txt;
echo -e "\e[0m";
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