cat is a Unix utility used for concatenating files.

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1answer
29 views

top not showing the memory usage of cat

I wanted to generate some waste file of 50 GB. so i wrote this eightnoteight@mr:~/ while true; do > cat txt >> tmp > cat tmp >> txt > done and when i ran top,watch to observe. ...
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2answers
39 views

Are `less textfile | col` and `cat textfile` the same?

Do less textfile | col and cat textfile accomplish the same thing? I wonder if man mysql | col -b > textfile and man mysql > textfile do the same?
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2answers
184 views

Why does cat x >> x loop?

The following bash commands go into an infinte loop: $ echo hi > x $ cat x >> x I can guess that cat continues to read from x after it has started writing to stdout. What is confusing, ...
4
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6answers
411 views

Command to output file content to stdout?

I know cat can do this, but its main purpose is to concatenate rather than just displaying the content. I also know about less and more, but I'm looking for something simple (not a pager) that just ...
1
vote
1answer
212 views

What does this `cat` statement do?

I'm new to Linux and trying to figure out what this statement in a Bash file does. I think it combines stdout, stderr and output it to the file $log is pointing to and append the multiline string to ...
0
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1answer
17 views

find file read it and search for specific identifier

I'm trying to find out in what files some specific identifiers are being used. I know the file's name and know the identifier, therefore I use the following command to achieve my desired result: find ...
1
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1answer
51 views

cat combining not all file formats - but which ones?

In GNU⁄Linux, combining files with cat works in miraculous ways – at least for me: cat part_* > /destination/file.xyz with the same file format for BOTH source and target file(s) ...
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0answers
31 views

Edit a command? [duplicate]

I'm using many basic commands of unix/linux. In Mac OS X Mavericks, I type cat for a file, but output was faulty. In example, content of the file named bar: foo bar Then: ...
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3answers
99 views

cat /dev/null emptied my log file but size did not change

I'm quite new to Unix. Using Solaris 10 I faced the below issue. There is a large log file with size 9.5G. I tried to empty the file using the below command. # cat /dev/null file_log.txt By doing ...
4
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2answers
167 views

How to pipe a remote file to stdout over scp or sftp?

Using ssh, it is easy to print the contents of a file using ssh host 'cat file.txt' When ssh is disabled, and only SFTP is enabled, running the previous command gives the following error: ...
3
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1answer
53 views

Does cat never read from terminal?

Chapter 43. Redirecting Input and Output of Unix Power Tools, Third Edition has to say this about cat command: Standard input (stdin) normally comes from your keyboard. Many programs ignore ...
4
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2answers
120 views

(cp is to cat AS mv is to ?) mv multiple files into one file instead of cat * rm *

For everything in this question pretend the system only has one disk and filesystem. (we are not writing to different partitions, disks or filesystems) I am working on a project that cats very large ...
2
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2answers
55 views

Backed up over wrong hard drive

I've just written over the wrong hard drive using the command: sudo sh -c 'pv /dev/sdb >/dev/sdc' How do I go about undoing this? I was creating the first even backup of the drive, and I backed ...
0
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2answers
25 views

concatenate .out files

Can I combined multiple .out files with the cat command in bash or csh? Additionally I want only the header of first file to be concatenated and I was thinking of using the tail function for that. ...
3
votes
1answer
55 views

How to set default tabs only for cat?

I prefer to set tabs 4 however this may have some side effects, such as for example ls out put may look not properly aligned. How might I configure the terminal / cat to use four spaces for tabs for ...
2
votes
1answer
140 views

How to interleave the lines of two or more files?

I have tried to get the 2 files output in a single file. I have tried below command: cat file1 file2 but here file2 data is appending to file1. What I need is file1 1st line followed by file2 ...
14
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2answers
1k views

How do I “cat and follow” a file?

A file is being sequentially downloaded by wget. If I start unpacking it with cat myfile.tar.bz2 | tar -xj, it may unpack correctly or fail with "Unexpected EOF", depending on what is faster. How to ...
4
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2answers
254 views

continuous reading from named pipe (cat or tail -f)

I have configured rsyslog to log certain log events to /dev/xconsole: *.*;cron.!=info;mail.!=info |/dev/xconsole /dev/xconsole is a named pipe (fifo). If I want to see what is being logged, I ...
0
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2answers
140 views

Passing a variable to a bash script that uses 'EOF' and considers the variable a literal [closed]

in this script i end up with "$1" being saved to the /test file. #!/bin/bash cat > /test << 'EOF' $1 EOF the truth is.. i need to keep 'EOF' as 'EOF' because my argument($1) contains ...
2
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2answers
116 views

“cat” command: how to automatically escape everything that might be a violation?

If you copy the contents of httpd.conf and then paste it into a cat command.. such as this one.. #!/bin/bash cat > /test << EOF pasted here.. EOF you run into this error: -bash: ...
4
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6answers
1k views

How to tell “cat” command to not hang on when there is no path provided?

I am simply trying to get a bash script to return the content of a text file. #!/bin/bash cat $1 the problem is.. when the path to a file is not fed to this bash script... how will it even close ...
0
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3answers
69 views

How to fork a “cat” command?

This is my bash script. #!/bin/bash oo="`cat /etc/httpd/conf/httpd.conf`"; cat > /a.txt << EOF $oo EOF it simply reads /etc/httpd/conf/httpd.conf and writes it to /a.txt, the problem has ...
15
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5answers
490 views

Is it possible to make zcat output text even if it's uncompressed? [duplicate]

The problem is I have some database dumps which are either compressed or in plain text. There is no difference in file extension etc. Using zcat on uncompressed files produces an error instead of the ...
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5answers
1k views

Difference between cat and '>' to zero out a file

Are these two commands any different on how they go about zero-ing out files? Is the latter a shorter way of doing the former? What is happening behind the scenes? Both $ cat /dev/null > ...
1
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1answer
132 views

Difference between cat * and cat * >>

To merge multiple files in a dir I have tried: cat * myfile.log but this seems to just merge line and line and is thus very slow So using instead: cat * >> bigfile merges the files much ...
0
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1answer
62 views

removing the last line of a file not working? [duplicate]

I have this TXT file that is created by a bash script and at the end I want to remove the last line of that file that is an empty one. head --lines=-1 r3.txt > r4.txt sed '$d' r3.txt > r4.txt ...
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99 views

cat echoes to serial port

Connecting my Windows PC to a Linux system (Wheezy) via the serial port (RS232) basically works except one problem when sending a message from the the PC terminal the Linux system. The reception of ...
4
votes
1answer
241 views

How can I get less or cat to use color in the output from .cat of my .bashrc, similar to vi 'ing it?

When I vi my .bashrc file it is colorized, i.e. but when I cat or less the file I get all white, i.e. How can I get cat (and less) to have color? cat does have color for my ruby .rb files but ...
4
votes
2answers
135 views

Spliting `File` and `directory name with space' via shell script

I've got a file called Files.txt having following content: TestApp/Resources/Supporting Files/main.m TestApp/Resources/Supporting Files/AppDelegate.h TestApp/Resources/Supporting Files/AppDelegate.m ...
8
votes
4answers
1k views

Why does “cat ttyUSB0” not produce output?

I connected an infrared receiver to a USB port ... (the last line of dmesg tells device file) $ dmesg [10496.596063] usb 7-2: new full-speed USB device number 2 using uhci_hcd [10496.751112] usb 7-2: ...
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2answers
646 views

Why using cat on binary files messed up the terminal and how?

If I understand correctly the cat manual: concatenate files and print on the standard output cat will take files as argument and print them on standard output. What I don't get is if I use the ...
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2answers
2k views

Fastest way to concatenate files

I've got 10k+ files totaling over 20GB that I need to concatenate into one file. Is there a faster way than cat input_file* >> out ? The preferred way would be a bash command, Python is ...
2
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1answer
73 views

< and << in UNIX /Linux

What is the option <<and < are used in linux for??? For example cat << abc.txt I know its a stupid question, but i was not able to search it on google as i did not know what ...
1
vote
1answer
118 views

Cat and Less give different output

I executed the following command # top > /home/user/top_output.txt Nothing Happened for a while and then i pressed Ctrl+C. When i checked the file that was created, it had the contents in it. So ...
4
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2answers
698 views

How can I get the tac command on OS X?

I like to use tac to reverse the output of cat. However, it's not available in the Mavericks terminal. I tried to find it on MacPorts and again it's not available. Can anyone please show me how to get ...
0
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2answers
484 views

How can I concatenate all files in a directory together in one command line operation? [duplicate]

I have 1000 csv files in a directory. I would like to concatenate them all together in order. They are named img_size_1.csv to approx img_size_1000.csv This answer is close but assumes a list file. ...
8
votes
4answers
2k views

Grep from the end of a file to the beginning

I have a file with about 30.000.000 lines (Radius Accounting) and I need to find the last match of a given pattern. The command: tac accounting.log | grep $pattern gives what I need, but it's too ...
2
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1answer
603 views

cat file to udp, pt 2: send 1 udp packet per ^C-delimited line

Yesterday I asked a question about catting a file over a UDP socket in bash. The solution we came up was netcat -c -w 1 -v -u -s 127.0.0.1 239.255.0.1 30001 < test.txt. This worked in the sense ...
2
votes
1answer
200 views

cat file to multicast

I have a text file (test.txt) which represents captured network data. The actual protocol is text-based, with NULL line endings, so this isn't a problem. I need to run this test captured data ...
0
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1answer
122 views

Passing multiple scripts to shell over ssh

I have a somewhat lengthy script which sources other scripts to include the functions there. I'd like to execute this script remotely via ssh. Now I thought to make one script file of it (without ...
2
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3answers
843 views

Can't cat a file or make a directory: contradictory output?

I am getting output from a terminal in Ubuntu 12 that I don't understand. $cat sublime no such file or directory $mkdir sublime cannot create directory 'sublime': File exists How can both of these ...
8
votes
1answer
1k views

How to store an image file in bash variable?

After I use the following command, pngString="$(cat example.png)" echo -n "$pngString" > tmp.png I can't open the tmp.png as a PNG file. Maybe some information is lost when I use $pngString ...
3
votes
2answers
442 views

How to highlight a word in the output of “cat”? [duplicate]

I can do the following to see if some word is available in the output of "cat": cat filename | grep word This filters the output and shows only those lines which contain "word". Now, is it possible ...
8
votes
3answers
416 views

Why does the less-than sign not work as a replacement for cat in bash?

I heard about "useless use of cat" and found some suggestions, but the following outputs nothing in my bash shell. < filename Using cat works as expected though. cat filename I'm using Fedora ...
1
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1answer
134 views

Cat write text with “$” inside

I want to write configuration information to a specific file which has dollar signs ($) inside. That seems to be a problem. Here's what I did: $ cat >> /etc/nginx/nginx.conf <<EOF # For ...
2
votes
2answers
429 views

How to mount bzip2-ed Clonezilla image without using extra drive space?

My hard drive seems to be failing and I suspect some data may be already damaged, so I decided to make an entire drive backup with Clonezilla using dd. I have chosen bzip2 compression to fit entire ...
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2answers
56 views

Concatenate a folder's Java files, with a header for each file

I have an obligation to provide a document which just contains every source code file, with the file's name before each file. Example: ============================= src/com/example/Factory.java ...
3
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4answers
148 views

saving output of another command

I need to select certain lines from the log file and also save them to a text file. I tried the following but none of them are working as expected. The file "todel.txt" shows 0 bytes. tail -f ...
3
votes
1answer
133 views

How can i colorize cat output including unknown filetypes in b&w?

I like the colors I have in vim. Can I get my output similarly colorized when I do a cat? I like that I can use the colorize tool as in Colorized `cat` for source and script files?. I would like that ...
0
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0answers
38 views

How to `cat` file with syntax highlight? [duplicate]

In my hello.c: /* Hello World program */ #include main() { printf("Hello World"); } How can i cat this file on terminal with syntax highlight?