Questions tagged [cat]

cat is a standard Unix utility used for concatenating files or printing specific file on the standard output.

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25
votes
1answer
6k views

How to implement a horizontal cat? [duplicate]

Standard cat concatenates files line by line (row by row, if you will). I find myself needing a horizontal cat command more and more often recently; i.e. a command that takes a list of files and ...
5
votes
2answers
8k views

How do I pass the contents of a file as a command line parameter

I am storing a file path in a file and need to pass the contents of that file as an argument to a shell script, specifically Maven, something like so: mvn -Dvar_name=(contents of file) Would this ...
1
vote
1answer
2k views

How to move files with same name and concatenate

My directory structure is given below. I need to move all the folders from Test3 to Test2 and concatenate the files with same names [jg@hpc Test2]$ tree . |-- Sample_1008 | |-- ...
17
votes
1answer
2k views

Make program first read from pipe, then from keyboard

Consider the interactive program interactive. I have to run this program fairly frequently, and each time I run it the first few commands are the same. Obviously, having to type those commands over ...
4
votes
2answers
323 views

Make ls distinguish scripts from binaries in output

Is it possible to make ls distinguish executable scripts from actual compiled binaries? The permissions are most often the same (+x), and with ls -F you get an asterisk suffix (*) for both, so it's ...
28
votes
1answer
21k views

Append same text to many files using cat or echo?

How can I write the same content to many text files by using cat or echo in only one command? For example I want to write "hello" to file1 and file2. I tried: echo "hello" >> file1 file2 but ...
11
votes
1answer
15k views

How to tail/grep/awk the last N bytes of a file, rather than lines

I have an application that is logging to a plain text log file (myapp.log) but it doesn't seem to be writing new line characters at the end of each log entry. If I execute a command like tail -n 50 ...
4
votes
3answers
8k views

cat corrupts serial port data

I have an application which writes some bytes to a serial port. When I do cat /dev/ttyS0 to see what is being transferred, I find that the data is corrupted by the cat command. Is there any other way ...
23
votes
9answers
53k views

Command to display first few and last few lines of a file

I have a file with many rows, and each row has a timestamp at the starting, like [Thread-3] (21/09/12 06:17:38:672) logged message from code..... So, I frequently check 2 things from this log file. ...
4
votes
1answer
4k views

File size limit exceeded in bash [closed]

I have tried this shell script on a SUSE 10 server, kernel 2.6.16.60, ext3 filesystem. The script has a line like this: cat file | awk '{print $1" "$2" "$3}' | sort -n > result The file's size ...
62
votes
6answers
65k views

Is there a simple command for outputting tab-delimited columns?

E.g. I have a file (produced with echo -e "var1\tvar2\t\var3\tvar4" > foo) that are output as: $ cat foo case elems meshing nlsys uniform 2350 0.076662 2.78 non-conformal 348 ...
126
votes
6answers
239k views

cat line X to line Y on a huge file

Say I have a huge text file (>2GB) and I just want to cat the lines X to Y (e.g. 57890000 to 57890010). From what I understand I can do this by piping head into tail or viceversa, i.e. head -A /...
4
votes
2answers
6k views

What is the difference between > and >> (especially as it relates to use with the cat program)? [duplicate]

Suppose that I have a file called temp.txt. Using the cat program, I would like to add the contents of this file to the end of myfile.txt -- creating myfile.txt if it does not exist and appending to ...
7
votes
7answers
11k views

cat files with directory

Is there a command to show the directory/file name when cat files? For example: assume two files f1.txt and f2.txt are under ./tmp ./tmp/f1.txt ./tmp/f2.txt Then when I do cat ./tmp/*.txt, only ...
6
votes
3answers
742 views

Gedit or an other non-commandline editor with the ability to spell-check two languages at the same time

I'm searching for an editor with the ability to spell-check two languages at the same time (German and English). Gedit can't do it out of the box. But I want to use Gedit. It should be possible by ...
7
votes
4answers
50k views

How to pause listing long text file with cat in command prompt after 10lines then press any key

How to pause listing long text file with cat in command prompt after 10lines then press any key. for example: cat myfiles.txt bla bla bla bla bla bla . . . bla press enter to continue
17
votes
4answers
10k views

Is it possible to merge video files using `cat`?

I wonder if it's possible to merge video files using the cat command? I mean will the resultant file play seamlessly?
3
votes
1answer
3k views

Write data to both a file and a serial port — can I use tee?

I am trying to take the input from a serial port and write it to a file and also then read the file and send it back out the serial port to the host computer. A coworker suggested using the "tee" ...
13
votes
2answers
21k views

Unexpected results testing serial loopback using echo and cat

So I have a standard RS232 serial port that is looped back to itself by simply running a wire from Tx to Rx. I'm testing loopback by running echo and cat in two separate terminals: cat /dev/ttyS1 ...
12
votes
2answers
2k views

How to use `cat` or `less` depending on the line count?

When looking at the content of files, I'd like to automatically cat short files but less those that exceed the screen size. I could use something with wc -l, but is there a better way that maybe also ...
10
votes
2answers
7k views

Why does `cat`ing a file into itself erase it? [duplicate]

Possible Duplicate: IO redirection and the head command I just wanted to remove all but the first line of a file. I did this: head -1 foo.txt ... and verified that I saw only the first line. ...
17
votes
3answers
42k views

How do I concatenate all the files in a given directory in order of date, where I want the newest file on top?

And with the oldest file on bottom? Also, if I do this, is it also possible to strip out the redundant headers contained within each HTML file? I'm seeing myself concatenate a lot of HTML files up, ...
4
votes
1answer
4k views

Command substitution: cat with executable content

I have a file called test and the contents are: ubuntu@regina:~$ cat test ** test ** catting this file via command line works fine, but if I use command substitution I get an understandable but ...
9
votes
3answers
3k views

Colorized `cat` for source and script files? [duplicate]

Possible Duplicate: How can I display syntax highlighting on a file? Is there any application like cat, but with color output? I'd like to view my files with colors like in any IDE's editor.
5
votes
4answers
8k views

concatenate two files without adding a newline

If I nano two files, one of which reads 'this' without me entering a newline, and one of which reads 'is' without me entering a newline, I want to be able to then cat the two files together into ...
15
votes
7answers
9k views

Change tab size of “cat” command

When I am in vim I can change the tab size with the following command: :set ts=4 Is it possible to set tab size for cat command output too?
5
votes
3answers
9k views

Concatenate specific files into one single file

In a folder containing X files, I need to concatenate Y files (where X > Y) together into a single text file. I have the filenames (of Y files) that I need to concatenate.
15
votes
2answers
8k views

How/Why does cat write a bootable ISO to a device

I recently discovered that I can create a bootable USB key from an ISO file by simply using cat (or dd). I can't find any information on how this works. Why would: cat my.iso > /dev/sdb &&...
4
votes
1answer
3k views

How to cat a file for a certain number of seconds? [duplicate]

Possible Duplicate: Run a command for a specified time and then abort if time exceeds Looked all over and I can't find the answer... Simple question: How can I cat a large file for, lets say, 45 ...
3
votes
2answers
1k views

Subtracting Binary files

I have 2 Binary Files FileA and FileC Its is such that FileC = FileA + FileB using the cat utility How do I subtract FileA from FileC to get FileB ? PS: I am using Ubuntu Oneiric
7
votes
6answers
5k views

How to avoid a useless use of cat when parsing a file?

I have a file containing a list of directories. For instance /foo/bar/dir1 /foo/bar/dir2 /foo/bar/dir3 I want to create all these directories. Here's what I did: for dir in $(cat myfile); do mkdir ...
27
votes
12answers
43k views

How can I “cat” a file and remove commented lines?

I'd like to know if there is a way that I could cat file like php.ini and remove all lines starting with ; For example, if the file contained this: ; - Show all errors, except for notices ; ;...
5
votes
5answers
1k views

Cat with Headers and Line Numbers?

I have files like this $ cat trapetz x = 0:0.0001:7pi plot(x, sin(x).*cos(x)) Area = trapz(x, sin(x).*cos(x)) $ cat simpson f = inline(sin(x).*cos(x)); Area2 = quad(f, 0, 7pi, 1e-16) I want ...
0
votes
2answers
2k views

Combination of ls, xargs and zcat leads to duplicate file name suffixes?

Disclaimer: Yes, finding files in a script with ls is bad, but find can't sort by modification date. Using ls and xargs with echo everything is fine: $ ls -t1 ssl-access*.gz | xargs -n 1 echo ssl-...
0
votes
1answer
2k views

Running md5sum on a file's contents

md5suming a file is fine, but I cannot seem to invoke md5sum to calculate the hash based only on the file's contents. (For those wondering, I'd prefer that multiple wgets of the same file return the ...
6
votes
5answers
670 views

Conflict between my prompt definition and cat in zsh

I have a file on a remote filesystem that I know has a short text string in it (a sequence of numbers in a single line). If I open the file on a text editor like nano or Emacs I can see the string. ...
58
votes
18answers
42k views

Is there ever a reason to use `cat` when you've got `less`?

I used to use cat to view files. Then I learned that less is usually better, and is a must if the file is longer than a few dozen rows. My question: Is there ever a reason to use cat instead of less? ...
42
votes
4answers
12k views

How can I display syntax highlighting on a file?

Is there a variant of cat that outputs syntax-highlighted lines of code when used on a source file? An idea: maybe vi[m] or another editor can be asked to dump the syntax-highlighted contents of said ...
9
votes
2answers
481 views

Weird control-d behavior

I can use cat as a very simple text editor by doing cat > foo.txt. If I then type: bar baz and then press ctrl+D, it now looks like this: $ cat > foo.txt bar baz^D with the cursor at the ^. ...
11
votes
2answers
3k views

Performance difference between stdin and command line argument

For some commands, it is possible to specify certain input as either stdin or a command line argument. Specifically, suppose command can take stdin input and a filename as command line argument, and ...
0
votes
1answer
332 views

Is 'some_program <some_file' faster than 'cat some_file | some_program'? [duplicate]

Possible Duplicate: Should I care about unnecessary cats? Both would be functionally equivalent, but when using cat wouldn't it be slower because you have a process first reading the file and ...
49
votes
4answers
5k views

Should I care about unnecessary cats?

A lot of command-line utilities can take their input either from a pipe or as a filename argument. For long shell scripts, I find starting the chain off with a cat makes it more readable, especially ...
120
votes
8answers
31k views

dd vs cat — is dd still relevant these days?

I recently realized we can use cat as much as dd, and it's actually faster than dd I know that dd was useful in dealing with tapes where block size actually mattered in correctness, not just ...
8
votes
2answers
2k views

What is produced after using cat on an image?

Let's say one creates a file like so: touch myFile You enter some text in it with vim or whatever, and then use cat myFile to spit the contents out into the terminal. Now, what happens when I use ...
5
votes
2answers
2k views

Encoding changed after running cat

After running cat on some files I get the infamous 'bushes': ␌⎺└⎻⎼␊⎽⎽␊␍ ├▒⎼ °␋┌␊. B␊├├␊⎼ ┤⎽␊ ├▒⎼'⎽ ≥ which I believe are result of encoding being changed. Is there any way to recover the terminal ...
42
votes
6answers
185k views

How can I read line by line from a variable in bash?

I have a variable which contains multiline output of a command. What's the most effecient way to read the output line by line from the variable? For example: jobs="$(jobs)" if [ "$jobs" ]; then #...