Pipes or named pipes are a feature of the POSIX standard that allow separate processes to communicate with each other without having been designed explicitly to work together.

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Command output redirection to vim not working on OS X

I'm trying to redirect the output of a command to vim using the - argument, but it doesn't seem to work on OS X. For example, if I type $ ls | vim - on the command line on one of my Linux ...
8
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6answers
4k views

Make a pipe conditional on non-empty return

Is there a way to pipe the output of one function to another, but only if there is an output?
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2answers
5k views

How to sort ls by column in Ubuntu via piping to sort?

I'm a Linux newbie trying to learn how piping works in the Ubuntu terminal. I tried to sort by file size: ls -al | sort -k5 The files were listed in this order: drwx------ 19 min10 domain users ...
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4answers
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Why does this not work? “ls *.txt | xargs cat > all.txt” (all files into single txt document)

Why does this not work? ls *.txt | xargs cat > all.txt (I want to join the contents of all text files into a single 'all.txt' file.) find with -exec should also work, but I would really like to ...
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2answers
857 views

pipe a program into less

I'm taking the dive into setting up and learning git and at the same time learning bash. I'm trying to do something simple as view the help section of $ git config unfortunately, when I type that ...
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7answers
8k views

Advantages of cat'ing file and piping to grep

Are there any additional advantages of cat'ing a file and piping it to grep, besides convenience? The convenience being that, when I retrieve commands such as those below from my history, the cursor ...
31
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4answers
45k views

How to pipe command output to other commands?

Example: ls | echo prints nothing ( a blank line, actually ). I'd expect it to print a list of files. ls | grep 'foo', on the other hand, works as expected ( prints files with 'foo' in their name ). ...
8
votes
4answers
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Bash: create anonymous fifo

We all know mkfifo and pipelines. The first one creates a named pipe, thus one has to select a name, most likely with mktemp and later remember to unlink. The other creates an anonymous pipe, no ...
2
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1answer
660 views

How do I run a command on each file within a directory that matches a pattern?

I'm trying to run a command on every file within a directory (recursively) that matches a pattern. I need the filename of each item that matches for the command however. This is how far I've got: ...
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2answers
664 views

Split an[d] archive large backup file in constant working space

I'm currently attempting to use tar and split to get DVD-sized archives of my Time Machine backup database. It's going to work this time, as I have a partition on my external drive large enough to ...
19
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4answers
21k views

cURL: how to suppress strange output when redirecting?

I'm trying to print just the verbose sections of a cURL request (which are sent to stderr) from the bash shell. But when I redirect stdout like this: curl -v http://somehost/somepage > /dev/null ...
4
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2answers
399 views

How to utilize vim's syntax color to replace the `highlight' utility?

I feel that the `highlight' utility doesn't support as many file types as vim does, and the project isn't very active. When the file is gzipped, highlight doesn't recognize it at all. But in ...
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1answer
2k views

Pipe grep exit code away

When I need to suppress some kind of output e.g. foo | grep -v bar But foo gives sometimes only: bar bar bar... grep will return -1. How do I transform the exit code 1 to 0?
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4answers
4k views

Rsync to stdout?

I have access to backup server via rsync protocol (only rsync, nothing else). Now, I want to fetch file from there (which is .tar.gz) and pass it directly to tar command, without saving the archive in ...
1
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3answers
952 views

Double pipes in Linux

Is it possible to do a command in Linux with "double pipes", like this? blah | blah | blah
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1answer
110 views

How to construct shell redirection on command line

Consider the following command in Unix: echo 0123456789 | cat >/tmp/foo &> /tmp/bar The echo is sent to /tmp/bar. However, what I really want is to redirect the stdout and stderr output ...
3
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2answers
2k views

gpg symmetric encryption using pipes

I'm trying to generate keys to lock my drive (using DM-Crypt with LUKS) by pulling data from /dev/random and then encrypting that using GPG. In the guide I'm using, it suggests using the following ...
1
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1answer
598 views

grep -v -A not working properly (actually not working at all)

I have to filter lines like the following: [javac] /Users/looris/Sviluppo/android/projects/toutry/src/net/looris/toutry/Stuff.java:23: warning: unmappable character for encoding ascii [javac] ...
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5answers
778 views

commands executing in piping in UNIX

when I write a command $ echo date then it prints "date" as it is i.e it doesn't run date program. But when I write $ echo date | wc then correct answer is produced as if date was run. How ...
37
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2answers
6k views

How to rate-limit a pipe under linux?

Is there a filter which I could use to rate-limit a pipe on linux? If this exists, let call it rate-limit, I want to be able to type in a terminal something like cat /dev/urandom | rate-limit 3 -k | ...
3
votes
1answer
701 views

Unix commandline to repeat command with pipes

I want to write a script that will repeat a commandline that usually contains pipes ./myscript.sh ls -lart |grep ^d And in myscript.sh I do a bunch of stuff, and then want to execute ls -lart |grep ...
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1answer
1k views

Making nano accepting previous piped output as a file path

When I run the following command in linux: find / -iname httpd.conf I get: /usr/local/apache/conf/httpd.conf I want to use nano to edit this file, lazy to type the file path again, I used: find ...
0
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2answers
953 views

Grepping grep output fails

I'm trying to grep the output of ngrep. Unfortunately when I add another grep to the pipeline, I get no output at all. It can be some other command too - cat / grep / tee - everything breaks the ...
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votes
3answers
3k views

Creating a named pipe on Windows

I want to write a large dataset from a SQL Server 2005 database using BCP (bulk copy program). Ideally I'd like to do the following: bcp MyDatabase..MyTable OUT STDOUT -c -t, |gzip -c ...
4
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1answer
1k views

emacs as a pager?

I am looking for a way to use emacs as my pager command in the shell (for example with man or to scroll the output of an asynchronous command with a large amount of output). I use emacsclient as my ...
3
votes
1answer
4k views

How do I pipe Java exceptions into a text file along with normal output?

When I use batchfile.bat >> logfile.txt command in the Windows commandline, it correctly outputs the normal output into the text file, but the Java exceptions get output to the console. Can I make it ...
8
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3answers
3k views

Does pipe have to write temporary file?

I found that if I transfer a great amount of data between two processes via pipe, some temporary file will be created by linux in /tmp directory. If the pipe operation succeeds, the corresponding ...
0
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1answer
1k views

piping curl's response headers

I'm getting weird results when trying to capture curl's response headers in a variable: pattern="< Content-Length: " val=$(curl --verbose \ --request POST --data "desc=hello world" \ ...
2
votes
1answer
164 views

Why doesn't “find -print0” work in Cygwin under Vista?

I'm writing a simple shell script: find datafiles/ -type f -print0 | xargs -0 md5sum > datafiles.md5 In Cygwin under Vista, it just sits there and nothing happens. It works fine on Linux. What ...
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3answers
2k views

xargs vs backtick

More silly questions from the Linux n00b. =D I'm curious about the performance ramifications of using xargs vs. backticks. For example, what's the different between: find ./ -name foo* | xargs rm ...
4
votes
2answers
1k views

Linux - Is there a way to convert .bz2 files to .tar.bz2 files using pipes?

Is there a way to convert a .bz2 file to a .tar.bz2 file without decompressing the entire thing to disk and then re-compressing? The decompressed size is larger than my drive. Since bz2 operates on ...
4
votes
4answers
10k views

I would like to pipe output of find into input list of scp, how?

I'm a novice linux user and I am trying to send a long list of files from one computer to another. The argument list is too long, so I am using find. I am having trouble setting up the expression, ...
8
votes
6answers
4k views

how to beep on tail -f event

I want my PC to make a system beep on every tail event I have the following command tail -f development.log | grep "something rare" is there an easy way like pipeing it to somthing that beeps? ...
115
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5answers
26k views

Less and Grep: Getting colored results when using a pipe from grep to less

I use the --colour option of grep a lot, but I often use less as well. How can I pipe grep results to less and still preserve the coloring. (Or is that possible?) grep "search-string" -R * --colour | ...