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Treat Command Output as a File

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# 1  
Old 09-30-2014
Question Treat Command Output as a File
Hi.

Before I've post this question, I have spent hours looking for the solutions but to no avail. Because I think it is possible but I just don't know what is the right keyword to search for.

Ok, basically what I want to achieve is really simple.

It's just that I don't want to write another file because it's merely based on the existing file content.

I have these two files:
Code:
$ pg source.list
CSM_CKC_INFO_20140925.csv@89049445
CSM_CKC_INFO_20140926.csv@74182043
CSM_CKC_INFO_20140927.csv@91001466
CSM_CKC_INFO_20140929.csv@454
CSM_CKC_INFO_20140930.csv@95508536
CSM_CKC_INFO_20141001.csv@67984672
CSM_CKC_INFO_20140928.csv@48531796

and
Code:
$ pg incomplete.list
CSM_CKC_INFO_20140927.csv
CSM_CKC_INFO_20140929.csv
CSM_CKC_INFO_20140930.csv

So, I just want to list out the missing line from incomplete.list against the modified version of source.list - source.lost
Code:
$ pg source.lost
CSM_CKC_INFO_20140925.csv
CSM_CKC_INFO_20140926.csv
CSM_CKC_INFO_20140927.csv
CSM_CKC_INFO_20140929.csv
CSM_CKC_INFO_20140930.csv
CSM_CKC_INFO_20141001.csv
CSM_CKC_INFO_20140928.csv

So, I have this command
Code:
grep -vxFf incomplete.list source.lost > missing.list

So is there any chance for me to avoid writing that new file source.lost which si simply based on this command:
Code:
cut -c 1-25 source.list > source.lost

Thanks a lot.
# 2  
Old 09-30-2014
Do you mean like this?

Code:
cut -c 1-25 source.list | grep -vxFf incomplete.list

This User Gave Thanks to Aia For This Post:
aimy
# 3  
Old 09-30-2014
Quote:
Originally Posted by Aia
Do you mean like this?

Code:
cut -c 1-25 source.list | grep -vxFf incomplete.list

Certainly!

Thanks a lot.

Didn't think of passing the it that way.

Anyway, is there any other way? Embrace the command with some brackets for example?

What is I have the 3rd argument to pass in similar way (to be treated as a file)?

Thank you.
# 4  
Old 10-01-2014
Yes what you describe is process substiution and it works like this:

Code:
grep -vxFf incomplete.list <(cut -c 1-25 source.list)

This User Gave Thanks to Chubler_XL For This Post:
aimy
# 5  
Old 10-01-2014
Quote:
Originally Posted by Chubler_XL
Yes what you describe is process substiution and it works like this:

Code:
grep -vxFf incomplete.list <(cut -c 1-25 source.list)

Thanks but I got this error:
Code:
sh: Syntax error: `(' is not expected.

# 6  
Old 10-01-2014
This is a fairly new feature and is not available in a lot of shells yet. I know it's supported in the bash shell and ksh93.
This User Gave Thanks to Chubler_XL For This Post:
aimy
# 7  
Old 10-01-2014
Quote:
Originally Posted by Chubler_XL
This is a fairly new feature and is not available in a lot of shells yet. I know it's supported in the bash shell and ksh93.
I see.

Thanks for your info.

But I just read somewhere that it is due to posix limited environment.

How do I check if my system supports it or not?

Because I think it's really cool if I could use my script that way.

Thanks.

---------- Post updated at 11:48 AM ---------- Previous update was at 11:40 AM ----------

I am using Bourne shell I guess.
Code:
$ ps
   PID TTY       TIME COMMAND
  1114 pts/te    0:00 telnetd
  1115 pts/te    0:00 sh
 10318 pts/te    0:00 ps

I there anyway that I can do to use this process substitution feature?

Thanks.

---------- Post updated at 11:51 AM ---------- Previous update was at 11:48 AM ----------

I can use
Code:
 grep -vxFf complete.list $(cut -c 1-25 source.list)

But it will read the file content Smilie
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