A script is a sequence of commands or instructions that are executed by an interpreter program rather than compiled into a standalone executable program.

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3answers
7k views

How to “send” variable to sub-shell?

I run the following script: VAR="Test" sh -c 'echo "Hello $VAR"' But I get : # ./test.sh Hello How can I "send" the variable VAR of my script to the shell created with sh -c?
3
votes
2answers
6k views

How to exclude a list of full directory paths in find command on Solaris

(Duplicated from Stack Overflow: http://stackoverflow.com/questions/7854975/how-to-exclude-a-list-of-full-directory-paths-in-find-command-on-solaris) I have a very specific need to find unowned files ...
2
votes
1answer
147 views

Start and stop multiple executable for easy debugging

I'm debugging a networking project, which involves interacting of 3 programs, ie a server, two different clients. However I find it difficult to start and stop them for debugging. Some methods I have ...
6
votes
5answers
14k views

Match regex in ksh

I am looking to do something like this in KSH: if (( $var = (foo|bar)[0-9]*$ )); then print "variable matched regex" fi Is it possible at all? For the record I'm using Ksh Version M-11/16/88i ...
1
vote
2answers
166 views

How to log if an environment variable is unset? [closed]

How can I write a shell script that checks for an environment variable and writes to a log file if the variable is unset? Also, if the file name pointed by env variable doesn't exist, how to create ...
1
vote
3answers
490 views

Evalute passed in variable in bash

Is there a way to pass in a variable as an argument to a bash script and have it evaluated scoped by the bash script? Given: # cat /path/to/file/of/host/names bob tom joe etc... # dofor FILE=$1 ...
5
votes
3answers
5k views

How to watch rss feed for new entries from bash script?

I need to watch a RSS feed from our hudson ci server. Each time a new entry is available i want to play a sound by calling #>play sound.wav. Does anyone know a tool which can watch a rss-feed and ...
5
votes
4answers
2k views

Last failed command in bash

The $? variable holds the exit status of last run command. Is there a variable that holds last run command itself?
1
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2answers
419 views

tail -f equivalent

I am seeing several seconds delay with the tail command. I found the cause for it has something to do with nfs services. I am using arch linux and yet to find out how to disable all these services I ...
10
votes
2answers
2k views

Piping for loop output prevents local variable modification

I'm trying to write a simple bash function that takes, as its arguments, a number of files and/or directories. It should: Fully qualify the filenames. Sort them. Remove duplicates. Print all that ...
6
votes
4answers
1k views

Shell programming, avoiding tempfiles

I often write KSH shell scripts that follow the same pattern: (1) retrieve output from one or more command (2) format it using grep|cut|awk|sed and print it to the screen or to a file In order to ...
4
votes
1answer
471 views

Alternatives to XDialog

Are there any alternatives to XDialog? Ideally something that would support both X server and terminal interface.
1
vote
2answers
1k views

How can I queue processes?

I have a surveillance camera and a program records videos when motion is detected. Basically, this program saves the video in a very heavy format. My solution was to call a script that converts the ...
6
votes
1answer
916 views

Automated incremental backups to an external drive

Background A client needs an automated backup solution to an external drive (to be taken offsite weekly). I'd typically suggest rsnapshot (or perhaps rolling out a custom rsync script), but this ...
2
votes
2answers
872 views

Comparing files and their properties

I get information of a certain set of files in my mail every day, which looks like this: 58623208 Sep 14 20:08 blbn_blfbe_drv 57904920 Sep 14 19:54 blbn_cycmn 55814208 Sep 14 06:02 clsa_Upd 38912000 ...
4
votes
1answer
2k views

shorthand for feeding contents of multiple files to the stdin of a script

Hi good people of this community, Say I have a script called script, that reads from stdin and spits out some results to the screen. If I wanted to feed it contents of one file, I would have typed: ...
4
votes
3answers
441 views

Should I be using 'sudo' in scripts that I write?

I'm setting up a new machine (well actually, an Ubuntu VM) and am trying to write a script to setup a few common things that I use when doing this (Git, curl, vim + janus). So my script looks a bit ...
3
votes
3answers
3k views

How can I test if a program is running from within a script

Let's assume that another user started a bunzip process, and I have a script that I'd like to start running after that bunzip finishes. What's the best way to check from inside my script that the ...
3
votes
1answer
2k views

How can I use imagemagick's identify command in a script to tell if a JPEG file is invalid or corrupt?

I have a somewhat-kludgey script in which I want to copy valid, complete JPEG files to a photo album directory. I thought I could use ImageMagick's identify command to do this. The web documentation ...
4
votes
1answer
196 views

Help improving my AWK skills

This program works as I intended but I feel like I used some clumsy methods to get the out put I desired(especially with my use of print commands and variable declarations) Could some one improve ...
2
votes
2answers
94 views

How do I execute a command on a given string in each line of a file?

Let's assume that I already have a file created. This file creation comes from the execution of a command. The contents of the file will be up to 4 different lines looking something like this: LUN ...
13
votes
3answers
1k views

How to make those old-school GUIs (like the debian/arch installer)

I've been doing a lot of installs lately, and when possible I usually opt for the text install from the Live CD's GRUB menu. Most installers looks like this: I always thought these GUIs (if you can ...
3
votes
2answers
76 views

Text files with sections in common with a given file

I need to maintain a set of plain text files saved in a directory which all have a section taken from another file. An example follows: Files: /directory/textfile1 (every other file in the directory ...
2
votes
1answer
715 views

How do I replace certain text with the respective line number using sed?

I have a file where certain (not all) lines look like so: Sequence: n I wish to replace n with the respective line number. How can I do it with sed?
4
votes
2answers
2k views

What does `export COLUMNS` do?

What is the significance of importance of the command export COLUMNS ? What I know is that it's a global variable. I frequently see it in the beginning of *nix scripts.
13
votes
9answers
35k views

Automatically run commands over SSH on many servers

There is a list of IP addresses in a .txt file, ex.: 1.1.1.1 2.2.2.2 3.3.3.3 Behind every IP address there is a server, and on every server there is an sshd running on port 22. Not every server is ...
2
votes
1answer
584 views

vim script: how to change “put =” to an append?

I'm trying to hack the c-vim plugin because I don't like the way it inserts comments. I want this: /* comment */ but it gives me this: /* comment */ I'm sure it has its reasons, but I don't ...
4
votes
2answers
3k views

Problem while running “newgrp” command in script

I want to change the working group in my script. So I wrote a line newgrp test_grp1 in my script. But my script is automatically exited after running this line. Are there any solution to overcome this ...
13
votes
3answers
10k views

Answer yes in a bash script

I'm trying to do a git clone trough a bash script, but the first time that I run the script and the server is not known yet the script fails. I have something like this: yes | git clone ...
4
votes
4answers
377 views

Generating sets of files that fit on a given media size for tar -T

Can anyone suggest a script that will take as input the name of one or more directories and a media size, and output lists of files for input to tar using -T (assuming no compression)? ...
3
votes
1answer
866 views

Make a failed SSH forward a fatal error

I have a script which connects to a remote host to replicate some files via SSH. I must connect to an rsync daemon listening on port 873. To accomplish this I have a ssh configuration like this. ...
3
votes
1answer
757 views

Change screen “hardstatus” color dynamically

I show the hard-disk free space in hardstatus screen. But also I want change the color of this value when it's less than a value to alert me. I have done a script that it checks this and it returns a ...
2
votes
2answers
532 views

Want a seperate file to store mysql username, password, and database name

I have as script that dumps a mysql database, and compresses the file. What I want to do is have another (edit) file which can change the username, password and database name. Then somehow connecting ...
9
votes
3answers
12k views

What is IFS in context of for looping?

I'm learning bash scripting right now. I was reading this thread: How to loop over the lines of a file? What is IFS? With for and IFS:
9
votes
1answer
1k views

confirmed exit using trap

I am trying to trap the Ctrl+C signal asking a confirmation from the user. The trapping part works fine. But once the signal gets trapped, it does not return to the normal execution. Instead, it quits ...
1
vote
1answer
2k views

What does “sudo chown -R hadoop:hadoop hadoop” do?

I saw the following script, posted online, that was used during the hadoop installation process. sudo tar xzf hadoop-0.20.2.tar.gz sudo mv hadoop-0.20.2 hadoop sudo chown -R hadoop:hadoop ...
13
votes
3answers
4k views

The way to use `/usr/bin/env sed -f ` in shebang?

Typing /usr/bin/env sed -f in terminal works. But if use it as a shebang, #!/usr/bin/env sed -f s/a/b/ The script will be fail to execute: /usr/bin/env: sed -f: No such file or directory I ...
2
votes
4answers
3k views

Is it possible to execute a VIM script in a non-interactive mode?

The Gnats bug tracker has a command (edit-pr) that opens a ticket in $EDITOR. My $EDITOR is VIM, and when this command opens the ticket in $EDITOR, I'd like to automatically perform some scripted ...
2
votes
2answers
3k views

Using sed to replace a line with many special characters?

I am writing a rather massive script for a project and one of the issues I am running into before I can complete it is using the sed command. I am trying to find a line that has (located in ...
1
vote
1answer
200 views

Mass update of /etc/ldap.secret

I have a group of servers authenticating against an LDAP server. I would like to be able to periodically update the /etc/ldap.secret file with an updated secret. I've written a small script that reads ...
4
votes
1answer
3k views

How can I automatically restart gnome-shell coming out of suspend mode?

So, due to an issue with gnome-power-manager, gnome-shell, and my nvidia card, I'm left in the awkward position of coming out of suspension/sleep with my graphics broken. This problem resolves itself ...
3
votes
1answer
4k views

auto accepting rsa key in bash script

I have done a little googling and have not come up with a clear answer to this question. I was wondering if someone could help me out with this issue. Is there a way to auto accept any RSA key inside ...
0
votes
1answer
242 views

sudo nt passing after redirection operator [duplicate]

Possible Duplicate: sudo permission denied but su grants permission I am trying to echo a new value into a file using following command sudo echo 4096 > /proc/sys/fs/file-max The ...
7
votes
2answers
1k views

How to do a text replacement in a big folder hierarchy?

I want to search and replace some text in a large set of files excluding some instances. For each line, I want a prompt asking me if I need to replace that line or not. Something similar to vim's ...
8
votes
4answers
315 views

Do you prefer bash scripts or aliases for shortcuts?

I have a ~/bin directory (which is on my PATH) where I store a lot of little 1 or 2 line scripts. Some of them just cd into a directory and run a command on a file, like vim or something. But I also ...
4
votes
3answers
10k views

checking an argument to a bash script is a string of all digits

The Bash FAQ says If you're validating a simple "string of digits", you can do it with a glob: # Bash if [[ $foo = *[!0-9]* ]]; then echo "'$foo' has a non-digit somewhere in it" else echo ...
2
votes
3answers
793 views

Batch File Rename Using Mapping File

I have a large collection of image files, for example: a.png, b.png, c.png, etc If I have a file with mappings of filenames to numbers, like so (ignore the format, it could be anything): a=>1 ...
4
votes
2answers
979 views

bash script is trying to execute a variable

I have a very short Bash script, like this: variable="3 things" if $(echo $variable|grep "^[0-9]\{1,\}") #if $variable begins with [0-9] then echo $(echo $variable|sed 's/ .*$//') else echo ...
20
votes
5answers
983 views

shebang and path

Why does a shebang need a path? Wrong #!ruby Correct #!/usr/local/bin/ruby #!/usr/bin/env ruby The operating system should have the information regarding the path for a registered command, and ...
8
votes
2answers
553 views

Command to move a window to all desktops

I'd like to be able to move (pin) an existing window to all desktops using a scriptable command, rather than through the window menu. wmctrl -r <WIN> -t <DESK> will move a window to a ...