small programs used on the command line to do a specific job

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4
votes
3answers
1k views

Why doesn't uname -a return a useful identifier

I typed the command uname -a into my college's server and got this: 2.6.18-274.3.1.el5 #1 SMP Tue Sep 6 20:14:03 EDT 2011 i686 i686 i386 GNU/Linux Are they trying to hide the version of Linux that ...
15
votes
4answers
6k views

Fix or alternative for mktemp in OS X

I'm looking at a bash script someone else wrote that uses mktemp: TEMP=`mktemp --directory` However, this line does not work on my machine (OS X 10.6). How would I fix this line so that it is ...
22
votes
4answers
1k views

Are Linux utilities smart when running piped commands?

I was just running a few commands in a terminal and I started wondering, does Unix/Linux take shortcuts when running piped commands? For example, let's say I have a file with one million lines, the ...
6
votes
1answer
425 views

Interactive tree command

Is there any version of tree command that displays file structure as a tree structure, but in a way that I can interactively walk trough? Why do I need it exactly - I am trying to simulate TextMate ...
4
votes
2answers
4k views

file block size - difference between stat and ls

I've noticed that when I do a: ls -ls file It provides block count, say 8 blocks. When I do: stat file I notice that the block count is 16, twice the number given by ls. The block size on my ...
12
votes
2answers
282 views

`test` and `[` - different binaries, any difference?

I noticed while answering another question that test and [ are different binaries, but the [ manpage pulls up test's. Besides the requirement for an ending ], is there any difference? If not, why are ...
2
votes
1answer
2k views

Listing a hardrive partition by blocks using LBA

Most hard drive and partition inspection tools seem to list the items using sectors, head.. etc. From another question I was told that these are virtual because they have to be converted from lba, ...
2
votes
1answer
830 views

How to plot the output of a command

How can I plot the output of this command line with GNUPlot? What should the diagram script look like? I want a histogram. wget -O - -o /dev/null http://www.stackoverflow.com/ | cat | cat | sed ...
4
votes
2answers
2k views

Set alignment of numeric columns when columnating data

I use column -t to format data for easy viewing in the shell, but there seems to be no option to specify column alignment (e.g. align to the right). Any Bash one-liners to do it? I have arbitrary ...
3
votes
2answers
97 views

Output the changes to a log file

If I use tail -f *filename* I get a real nice display of whatever is changing in a given file. However, sometimes I want to be able to search this text or otherwise look it over slowly. Is ...
46
votes
6answers
64k views

How can I use sed to replace a multi-line string?

I've noticed that, if I add \n to a pattern for substituting using sed, it does not match. Example: $ cat > alpha.txt This is a test Please do not be alarmed $ sed -i'.original' 's/a test\nPlease ...
9
votes
4answers
8k views

creating a sequence of numbers, one per line in a file

Is there a way to create out of thin air, a file that is a sequence of numbers, starting at a given number, one per line? something like magic_command start 100 lines 5 > b.txt and then, b.txt ...
3
votes
1answer
1k views

installing column unix utility on windows

I would like to be able to use the BSD unix utilities: column, join and paste in my Cygwin installation. It seems that they are not available, or I cannot find them. Is there a way to install them so ...
2
votes
1answer
1k views

How synchronize two disks (or folders) using symbolic (or hard) links (like rsync)?

I'm searching a tool or a shell script or another program to synchronize two or more folders or disks. But it differs of rsync tool, because, I don't want to duplicate the missing file, but do a ...
2
votes
1answer
85 views

How to use the -t option of Unix command look

I'm learning the look utility and I don't understand the meaning of the -t option. Can someone show me some examples of it? I read the man page, but still don't know what it exactly means.
4
votes
2answers
10k views

Why is 'df' hanging?

I have recently been having problems running df, where it just hangs. Here's strace output, and in it, you'll see that I killed since it was just sitting there: $ strace /bin/df execve("/bin/df", ...
3
votes
2answers
106 views

Unatended script execution in ubuntu terminal

I have installed Ubuntu on a VMWare virtual machine. When I got to installing a VMWare tools, I have stumbled upon a simple question: If I execute a script (perl script in VMWare tools case), is ...
7
votes
2answers
641 views

What commands have -h human readable option, and how can I enable it by default w/env variable?

I'm tired of using aliases or typing -h. I want human readable output 24/7. Is there a way to enable it all the time for all commands that offer it?
5
votes
1answer
144 views

How would one detect if external command exists in a script?

Is there a way to detect if an external command exists (i.e. wget, svn)? More specifically today, i was trying to run one of my scripts i wrote and the person didn't have wget or svn installed. The ...
0
votes
0answers
30 views

Problem with calling program from the command line [closed]

Note: this is a cross post with this post on SO. I am trying to build a command line wrapper in Python 3 for an exiting command line tool called 'spooky' and I am having a hard time understanding ...
0
votes
1answer
426 views

Listing only the files in a folder and inside its subfolders

Is there a linux command for getting only the files in a folder and inside its subfolders? I have used the find command, but it is displaying all the files and folders. I am executing this shell ...
3
votes
2answers
238 views

ln gives different results when run multiple times

I have this simple script to use with seventh sense (it's a lone wolf gamebook reader/player): #!/bin/bash GAME_PATH=$(dirname "$(readlink -f "$0")") SEVENTH_SENSE_PATH=$(echo ...
7
votes
2answers
661 views

Can hd and od replace each other?

hd and od are both dump viewers of binary content. Can hd be used wherever od is and vice versa?
1
vote
3answers
769 views

How to determine which executable on my path will be run?

I run which and get the following, brendan$ which python /opt/local/bin/python brendan$ which -a python /opt/local/bin/python /usr/bin/python brendan$ ls -l /opt/local/bin/python lrwxr-xr-x ...
1
vote
1answer
585 views

Good “progress bar” about md5sum checking progress?

I'm using this right now: time md5sum -c *.txt | pv | grep -v ': OK$' but aren't there any smart solutions that can list that how many files haven't been checked? I mean I have many md5sum's in ...
27
votes
4answers
34k views

Usage of dash (-) in place of a filename

For a command, if using - as an argument in place of a file name will mean STDIN or STDOUT. But in this example, it creates a file with the name -: echo hello > - How can I make - in this ...
4
votes
3answers
490 views

General specification for command line interface

I was wondering where I can find and learn some general idea about the command line interface used in Linux and bash? As to now, I have found pieces of such information only from experience, such as ...
6
votes
2answers
25k views

How do I get UUENCODE to work?

I have a server that I have inherited that has an older version of Redhat installed due to software requirements and now there is a need to use UUENCODE to allow email attachments. The uuencode and ...
3
votes
1answer
128 views

Colour problem when capturing a png of the top panel of the screen

I want to capture a window as a png from within a bash script, using the window's ID. In this case, the window is the top panel.  Using gnome-screenshot the colours are true, as per this image... ...
7
votes
7answers
12k views

How do I find the X window ID under the mouse pointer in bash?

From a bash script, is there some way to get the ID of the X window under the mouse pointer? (edit) I need the process to be non-interactive.
4
votes
2answers
255 views

Why do I get a 'conformability error' when I attempt to convert water in GNU units?

I've been using the GNU units program and I seem to think that I should be able to convert water between a volume and a weight. Examples: You have: 1 gram water You want: cm^3 conformability error ...
7
votes
7answers
25k views

Console tool to test internet bandwidth

I'm looking for a tool that will test my internet connection bandwidth and create an simple report like speedtest does. Do you know some program/tool that do this? Something with CentOS packages ...
7
votes
3answers
1k views

Combine input from multiple files/pipes without clobbering lines or blocking?

Is there a tool that will take input from multiple files or pipes and write it to stdout, without blocking on reads, such that individual input lines come out intact? I basically want to multiplex a ...
12
votes
2answers
2k views

Is '-9' a flag to kill command?

What does -9 do? It does not show up in the syntax: $ kill kill: usage: kill [-s sigspec | -n signum | -sigspec] pid | jobspec ... or kill -l [sigspec] $
1
vote
3answers
353 views

Sort data on multiple columns

INPUT (unsorted, bad) "XYZ-ZTE-43255 serverB618 agreed","XYZ-ZTE-44432" ,"XYZ-ZTE-43255" "XYZ-ZTE-52775 serverB110 agreed", "XYZ-ZTE-79213 - serverB688 agreed", "XYZ-ZTE-77323 serverB617 agreed", ...
1
vote
1answer
2k views

e2fsck progress bar?

How can I see the progress of e2fsck in the terminal? Are there any pv like ways? For example how can I see how far along this command is in progress: e2fsck -f -y -v /dev/sdb1
6
votes
4answers
2k views

In UNIX, how to find the most commonly used commands in history of unix?

In UNIX, how to find the most commonly used commands in history?
8
votes
5answers
35k views

How to recover data from a bad SD card?

I have a 4GB SD card with some family pictures on it that I need to recover. When I insert the card into my card reader, it shows up as an unknown 32MB device (as /dev/sde) and cannot be mounted. When ...
4
votes
2answers
905 views

Why is bash completion of a symlink different than a directory?

I usually do a find with an environment variable as the path when searching for source code. Recently I replaced my environment variable with a symbolic link, and it broke Bash's shell completion. ...
16
votes
3answers
3k views

Why use superflous dash (-) to pass option flags to tar?

To create a tar file for a directory, the tar command with compress, verbose and file options can be typed thus: $ tar -cvf my.tar my_directory/ But it also works to do it this way: $ tar cvf ...
12
votes
5answers
5k views

Alternative to find?

Is there an alternative find program with a more conventional CLI interface? find works and expects parameters in a painfully different way from most other utils. Clarification: I'm looking for a ...
2
votes
1answer
47 views

Explain the output of -D rates in GNU find

I did ~/pythonsource1/python2.6-2.6.5$ find -D rates . -type d and got Predicate success rates after completion: [need type] -type d [0.4] [280/4350=0.0643678] -a [0.4] [280/4350=0.0643678] ...
2
votes
1answer
530 views

ntop versus mrtg

I'm evaluating tools for measuring network activity and although mrtg seems to be the most highly regarded, I'm really impressed by ntop. Are there any reasons that mrtg is preferred to ntop?
1
vote
1answer
83 views

Good base converter or help using gbase?

Dear all, Could you suggest a good base converter that also does "signed" conversions? Either gbase does not do it, or I can't see how it's done. Any help would be great. What I want to do is give the ...
10
votes
2answers
23k views

How can I test the encoding of a text file… Is it valid, and what is it?

I have several .htm files which open in Gedit without any warning/error, but when I open these same file in Jedit, it warns me of invalid UTF-8 encoding... The html meta tag states ...
35
votes
4answers
5k views

What is the difference between a builtin command and one that is not?

Is there any intrinsic difference between a builtin command and another command which can nominally do the same thing? eg. Do builtins get "special" treatement? ... is there less overhead running ...
116
votes
3answers
29k views

What does “--” (double-dash) mean? (also known as “bare double dash”)

I have seen -- used in the compgen command. For example: compgen -W "foo bar baz" -- b What is the meaning of the --.
38
votes
8answers
8k views

Linux tools to treat files as sets and perform set operations on them

Does anyone know of any linux tool specifically designed to treat files as sets and perform set operations on them? Like difference, intersection, etc?
9
votes
2answers
5k views

How do I time a specific command?

(The linux equivalent of TimeThis.exe) Something like: timethis wget foo.com Receiving foo.com ... wget foo.com took 3 seconds.
32
votes
4answers
26k views

What is the mknod command used for?

I just started using Ubuntu as my main OS and I wanted to learn about things I should not do, and learn by the bad things people have done in the past. I came across these email about horror stories ...