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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4
votes
3answers
858 views

Why read works if stdin is redirected to fd4?

What does the following script mean? exec 4<&0 0</etc/XX/cfg read line1 exec 0<&4 It redirects fd0 to fd4, and "/etc/XX/cfg" to fd0. So why does read still work, shouldn't that ...
10
votes
9answers
25k 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 ...
0
votes
1answer
25 views

Filtering Log Output on Separate Lines

I did a recursive grep in a directory to find all files that would match as follows grep -ER "match_string1|match_string2" /path/to/dir/ What I get as output is: ...
6
votes
1answer
636 views

Can capabilities be used in scripts without setcap'ing the interpreter binary?

Right now I'm using cap_net_bind_service MY_USERNAME in /etc/security/capability.conf. Now I just need to set cap_net_bind_service+i on the interpreter of my favouite scripting language to be able to ...
0
votes
1answer
1k views

How to execute grep in tcl for getting XYZ-123 type pattern

How can I execute this grep command in TCL? grep '[A-Z][A-Z][A-Z]\-[0-9][0-9][0-9]' file1 > file2
-2
votes
2answers
69 views

Parsing a flat file using shell script

I have a file like in following format User:blala Pass:blala IP:***.***.**.** I tried with IFS but it is not working input="/path/to/your/input/file.cvs" while IFS=',' read -r f1 f2 f3 f4 f5 f6 ...
2
votes
1answer
35 views

Shell Scripting: Deleting or moving files from one directory that match filenames from another directory

I have a very specific and odd problem to solve. I'm working as a research assistant and I've been producing a ton of figures. In one directory, I dump .pngs to view casually (limited space here) and ...
1
vote
2answers
74 views

Capture errors in a SFTP script

I have a sub sh file which puts receives an input of local directory and path to the remote directory and sends the file to the remote directory. If the remote path is invalid the error cannot be ...
-1
votes
0answers
7 views

rpm package not updating as I update the spec file

I have some statement the %post section of my rpm spec file of the form echo "printing A" I updated the spec file to make it "printing B" but the new rpms I'm creating still echo "printng A" What ...
11
votes
3answers
6k 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?
0
votes
1answer
24 views

How to execute several lines into a .txt

I am using SSH; In a folder I have the next files: -rwxrwxr-x 1 german german 48 Apr 29 10:45 prueba.txt -rwxrwxr-x 1 german german 23 Apr 29 10:43 script1.sh -rwxrwxr-x 1 german german 23 Apr ...
0
votes
1answer
41 views

Script for update

I need your help in a script used for update : OLD="int 10" NEW="int 20" i=0 DPATH="/home" for f in $DPATH do sed -i "s/$OLD/$NEW/g" $f let i++ echo "modified:" $f done what i need ...
3
votes
1answer
243 views

How to make a PAM substack “requisite”?

For the auth section of my PAM configuration, login and mdm etc. call common-auth. I have common-auth calling the following as a substack (as auth substack krb5ldap-cache-auth): auth optional ...
3
votes
2answers
51 views

Detect and respond to ping in userspace

Is there a way to make a linux system react or do something when pinged from another device, besides just sending a reply (or not)?
2
votes
2answers
47 views

Does zsh expansion work differently in non-interactive scripts?

I'm currently working on a pretty simple zsh script. What I often do is something like: mv */*.{a,b} . When I run that within a zsh script, it seems to expand differently and fail while it works in ...
7
votes
2answers
1k views

How to make a temporary file in RAM?

I have a script that will pipe its output to |tee scriptnameYYMMDD.txt. After each cycle of the for loop in which the output is generated, I'll be reversing the file contents with tac ...
1
vote
1answer
49 views

Extracting duplicity backup data

I've made some backups of my previous systems using Deja Dup (duplicity). In my current distribution it's not available, so I've simply extracted the data. Now in order to make that data meaningful ...
0
votes
2answers
31 views

Add some text while output to file

Assume I have this command: ./clang-$j.out >> clang-result.txt and the each output for clang-$j.out is a fixed-length hash value (each program per line), however, I want to distinguish them by ...
9
votes
2answers
415 views

Jump out of a process when it get stuck

I have written a loop to iterate all .out c binary file and copy their outputs into a text file (the output for every binary file is just a one line hash value, one line output for one program). Here ...
2
votes
1answer
56 views

How do you make a toggle key using Autokey?

I want to use Autokey to toggle the e key on and off in a program called "xyz". So if I press e, the program thinks I'm holding down e. I press e again, it thinks I released it. How do you do this ...
2
votes
1answer
29 views

How do I detect which device was recently created by pppd?

I'm trying to setup a VPN over SSH using PPPD (following the Arch Wiki). The command given is: /usr/sbin/pppd updetach noauth silent nodeflate pty \ "/usr/bin/ssh root@remote-gw /usr/sbin/pppd ...
1
vote
1answer
560 views

Nmap script execution to detect heartbleed is failing

Wanting to setup Nmap on my Ubuntu 14.04 LTS system to detect HeartBleed vulnerability. I followed the instructions here: ...
0
votes
1answer
80 views

Run script on multiple hosts [duplicate]

I have below script which creates user list and also filters ignore.txt file to ignore matching usernames. I would like to run this script on multiple hosts like hostA, hostB, hostC. Like if I run on ...
3
votes
3answers
652 views

Averaging output of dstat

I need to average upload and download speed using dstat -n. How can I add all the received and sent data sizes that appear after dstat -n, so that I can add them and find average upload and download ...
1
vote
0answers
23 views

Need help with a network manager command line script

I am looking for some help in creating a script. As RHEL boots up and I login, I'd want to manually run a script which would: Identify the active ethernet interface (the eth ID being used). Ask ...
-3
votes
3answers
77 views

Delete line from files

I have 8 files in a folder. If any of these files has 2 lines I need to remove the second line from that file. If a file has more than 2 lines then then I do not need to do anything to it. Can anyone ...
1
vote
1answer
41 views

delete redis keys that have been inactive for 30 days

I've installed a web app called scrumblr which uses redis as a database. What I am attempting to do is delete all keys that have been inactive for 30 days, or have not been accessed in 30 days. I ...
2
votes
2answers
77 views

Change Password Programmatically

In the current version of Raspian, I know it is possible to change the password of the current logged in user from the command line like so: sudo passwd which will then prompt the user to enter a ...
0
votes
1answer
69 views

How to parse an awk variable

I'm trying to pull some information out of a log file, looking back over a specific period of time (e.g. the past hour). I've found the following awk construct that works, capturing the data as a ...
1
vote
0answers
20 views

How to disable AC power supply from CLI

This article among others suggested the following to prolong battery life: Keep cool. Operate in mid SoC of 20–80%. Prevent ultra-fast charging and high loads (most Li-ion) The main issue here ...
1
vote
1answer
34 views

How to change configuration of detox (dash instead underscore)?

I found, best to this moment, a solution when changing all those annoying filenames in large quantities, making them readable and easier to manipulate with in command-line. So I found, among many ...
0
votes
1answer
34 views

Filter grep output

Using grep "val" index.php I get the list <td class=val> 7.6</td> <td class=val> 58</td> <td class=val>1013.8 </td> <td class=val> 1020 </td> <td ...
0
votes
1answer
19 views

Connecting to Windows server from unix through script

I am trying to connect to a Windows server say 10.1.1.10. This servers has a folder named RAJ in which there are multiple .zip files. All these zip files contain a text file called XYZ.txt. Now i have ...
0
votes
2answers
37 views

Change only the year on the output of the “date”-command

date for example displays Fri Apr 17 20:16:01 IST 2015 Now I want to change only the year so date should display Fri Apr 17 20:16:01 IST 2016 in this example. How to add 1 year to the output of date ...
2
votes
3answers
75 views

Command line options with argument in shell script

I have a script to get ldap user name, email and mobile number: #!/bin/bash echo -n "Enter Unix id > " read UNIXID ldapsearch -x "(cn=$UNIXID)" | awk '/givenName/||/mobile/||/mail/' Here is the ...
4
votes
2answers
200 views

Best and short way to run a program if another is not installed

I have this code: #!/bin/bash num=${1:-undefined} cmd=$(which {banner,echo} | head -n1) until [[ "$num" =~ ^[0-9]+$ ]]; do read -p "Type a number: " num done for ((num;num>=0;num--)); do ...
187
votes
23answers
119k views

Repeat a Unix command every x seconds forever

There's a built-in Unix command repeat whose first argument is the number of times to repeat a command, where the command (with any arguments) is specified by the remaining arguments to repeat. For ...
2
votes
1answer
44 views

Storing one bit of information in user space [closed]

I'm writing a program that collects network data. I need to store one bit of information, a simple yes/no, somewhere so another process may read it. I have several options: writing a 1 or 0 to a file, ...
0
votes
0answers
25 views

Create complex installation script for Linux (Centos)

For deployment of a complex system I would like to create a script that runs all compilations and set up. I am looking for an existing product that interpret installation scenario and performs all ...
2
votes
2answers
334 views

How can you get ping to print human readable timestamps?

Ping can print you a timestamp on every line but its in unix date format :( ping -D localhost PING localhost.localdomain (127.0.0.1) 56(84) bytes of data. [1415629479.482938] 64 bytes from ...
0
votes
0answers
43 views

Need to have password coded in script [duplicate]

I have to login many Servers day in day out by supplying passwords manually. Now I want to know or have a script where from I can login to any server without password (I mean to say if the ...
3
votes
0answers
31 views

Automatically restarting process in the X server

I would like to know how to have a process that starts with the X server and automatically restarts when it stops running. I am running Ubuntu 14.04 with a KDE 4.13.3 desktop. I am running the ...
3
votes
3answers
75 views

How to run a script on a remote host when I lose connection to it?

I'm working with the BeagleBone Black, which runs Debian Linux, and sometimes I will lose wireless connection to it while I am testing my programs. This wouldn't necessarily be an issue on its own, ...
1
vote
1answer
133 views

Sed command that would ignore any commented match

I'm trying to create a sed command using regex in order to substitute something in a text file only if it is not commented but I'm running into some troubles due to my almost non-existent knowledge of ...
21
votes
12answers
8k views

Object-oriented shell for *nix

Preface: I love bash and have no intention of starting any sort of argument or holy-war, and hopefully this is not an extremely naive question. This question is somewhat related to this post on ...
0
votes
0answers
19 views

check media resolution if resolution is big ffmpeg it, if output is smaller than original delete the original else delete the output

I have my storage VPS filled with videos, and hoping I can free up some space, their resolution is pretty big so I decided to re encode them with ffmpeg to a smaller resolution, I am doing every thing ...
0
votes
2answers
47 views

How to search recursively in a directory for different files?

I have a x.tar file in directory /a. After untaring x.tar I got the following result: cust/ cust/01/ cust/01/INFENG/ cust/01/INFENG/scr/ cust/01/INFENG/scr/test.scr cust/01/INFENG/SQL/ ...
2
votes
3answers
114 views

remove all instances of _000 from multiple files

Had to recover my music library from a HDD which died.... got everything I wanted but all music track names have _000 added at the end. I really don't fancy going through 8000 individual music tracks ...
4
votes
2answers
116 views

Safely exiting while loops in bash

Say I have a bash script that does: while : do foo done I would like to be able to run this script from the console and be able to exit it at an arbitrary time as long as it happens in between ...
2
votes
3answers
179 views

AWK & Bash: Checking that a User's Home is Owned by the User

I'm trying to cycle through /etc/passwd with a single-line command in order to find those users who have a home directory which is not owned by the user, but I'm VERY new to bash programming, and I ...