Bash is the Bourne Again SHell, the successor to the classic Unix sh (shell).

learn more… | top users | synonyms (1)

4
votes
3answers
7k views

Bash prompt on Ubuntu - FQDN (\H) same as hostname (\h)

We've got seperate environments at my workplace for development, testing, integration, and staging. Within those envs, we've overloaded the hostnames in DNS - e.g. in the dev environment, the primary ...
2
votes
4answers
7k views

Command does not execute in crontab while command itself works just fine

I have this script from Colin Johnson on Github - https://github.com/colinbjohnson/aws-missing-tools/tree/master/ec2-automate-backup It seems great. I have modified it to send email to myself every ...
16
votes
1answer
790 views

can't type lower cased e in amazon ec2 (Amazon Linux)

After a few days of operation on my new ec2 build, the following happens: I log into SSH, everything is fine, I do my coding I return the next day, and log into SSH I cannot type a lower cased e ...
6
votes
2answers
958 views

How to find out if an OpenSSL certificate was created by a certain private key?

I have an OpenSSl certificate. I also need the private key. I was told it is located somewhere on the server, and true enough, I found multiple SSL key files. Before I try them all by brute force: Is ...
5
votes
4answers
3k views

less with “update file” like functionality

I want to watch a file that gets overwritten every 5 minutes with less. How can I make less follow the new file descriptor instead of keeping the old one displayed? watch "cat file" won't do it ...
3
votes
1answer
1k views

How to detect, in the guest operating system, if the vmware tools are out of date?

I'm trying to find a generic way of checking, in the guest operating system of a virtual machine, if the VMware Tools are out of date. The best way I have found so far has been to check the output of ...
2
votes
4answers
268 views

List all empty folders

I have a bunch of nested folders. Most folders contain files. Some contain hundreds of thousands of files. Some are empty. I want to get a list of all empty folders. However, when I run: find ...
0
votes
2answers
287 views

bash stuck at 3.2-24.el5 (Redhat)

I'm trying to update bash on our Red Hat Enterprise Linux Server release 5.6 server. But it won't find an update later than "3.2-24.el5". I've check and it is vulnerable for the shellshock ...
0
votes
2answers
215 views

Executing SU in a bash script

I'm running a remote bash script (using ssh -t 'bash doscript.sh'). In "doscript.sh" I have a sudo su anotheruser. At that point, the script seems to push a shell and I'm left in that "interactive" ...
6
votes
4answers
11k views

Is it possible to run a command on windows server from Linux?

I want to restore a sqlserver db backup on remote windows server from linux. I tired "net rpc" but there is nothing for execute a command or script on remote server.
5
votes
1answer
1k views

Shared Cygwin Install

I'm attempting to set up OpenSSH on a bunch of Windows Server 2003 machines in an automated fashion. My goal is to be able to do so using a single version of Cygwin installed on a network drive ...
2
votes
1answer
627 views

Binary won't execute when run with a path. Eg >./program won't work but >program works fine

I'm getting some weird behaviour for a binary file I'm trying to run. I'm using Mac OSX snow leopard, and the binary itself is part of labkey software .. built from source. If I try to run the file ...
1
vote
1answer
121 views

Disconnect modem when postfix queue empty

in /etc/ppp/ip-up.d/script I have the following that runs fetchmail when the ppp0 interface is up (connected) and when it finish the modem ends internet conection automatically. #!/bin/sh ...
0
votes
2answers
1k views

Can I use expect with SCP to bypass the password prompt?

I am trying to transfer some files using SCP in a shell script, but I am being prompted for my password on the remote machine. Can I use expect with scp to enter the password so I don't have to type ...
0
votes
3answers
5k views

crontab to run bash script (ssh command in it) not working

CentOS 5.4 (in my script file - script.sh) #!/bin/bash ssh 192.168.0.1 'iptables -L' > /tmp; (in /etc/crontab) 30 21 30 9 * root /bin/bash /script.sh If I run the script in terminal, things ...
-3
votes
2answers
47 views

How to compare today's date against an array of dates [closed]

I want to create an array of dates and compare it to today's date if it matches then execute test.sh file otherwise exit the loop in bash script. I have this so far: #!/bin/bash now=$(date +%Y-%m-%d) ...
53
votes
12answers
29k views

How can I run arbitrarily complex command using sudo over ssh?

I have a system that I can only log in to under my username (myuser), but I need to run commands as other user (scriptuser). So far, I have come up with the following to run the commands I need: ssh ...
61
votes
13answers
86k views

What's the best way to check if a volume is mounted in a Bash script?

What's the best way to check if a volume is mounted in a Bash script? What I'd really like is a method that I can use like this: if <something is mounted at /mnt/foo> then <Do some ...
53
votes
3answers
19k views

.profile vs. .bash_profile vs. .bashrc

what are the functional differences between these guys?
31
votes
7answers
93k views

How can I edit the welcome message when ssh start?

I have a vps for my website hosting. It is running a ubuntu server. Every time I logged in my server by ssh, it displays a lengthy welcome message in my terminal. Linux node61.buyvm.net ...
31
votes
6answers
22k views

Merge 2 directory trees in Linux without copying?

I have two directory trees with similar layouts, i.e. . |-- dir1 | |-- a | | |-- file1.txt | | `-- file2.txt | |-- b | | `-- file3.txt | `-- c | `-- file4.txt `-- ...
45
votes
8answers
48k views

How to make bash scripts print out every command before it executes?

For example, I have a simple bash file #!/bin/bash cd ~/hello ls How can I make it display every command before executing it? Just the opposite effect of "@echo off" in windows batch scripting.
29
votes
4answers
36k views

run script as user who has nologin shell

All I need to do is to run a specific script as a particual user who does have the nologin/false shell indicated in /etc/passwd. I would run the script as root and this should run as another user. ...
38
votes
1answer
10k views

What is the difference between a 'Login' and an 'Interactive' bash shell

What is the difference between a ‘Login’ and an ‘Interactive’ bash shell? I have quoted Wikipedia below but can anybody give a better answer? EDIT: This is a community wiki so maybe rather than ...
28
votes
4answers
11k views

Run an interactive bash subshell with initial commands without returning to the (“super”) shell immediately

I want to run a bash subshell, (1) run a few commands, (2) and then remain in that subshell to do as I please. I can do each of these individually: Run command using -c flag: $> bash -c "ls; ...
20
votes
8answers
15k views

How do I ask screen to behave like a standard bash shell?

Just learned about the screen command on linux - it is genius. I love it. However, the actual terminal/prompt in screen looks and behaves differently than my standard bash prompt. That is, the ...
7
votes
6answers
8k views

crontab environment

I have written various scripts to launch Java server applications, which are typically run for 24 hours before being shut down (by invoking the same script with a different parameter). The script ...
25
votes
2answers
21k views

How to apply a filter to real time output of `tail -f `?

tail -f path The above will output modifications to the file instantly, but I want to apply a filter to the output, only show when there is a keyword xxx in it. How to approach this?
14
votes
1answer
860 views

Can Bash Tell Me Which SSH Public Key Was Used To Authenticate?

Let's say I want to track my root users. Each of them has a unique private key and their public keys have been stored in /root/.ssh/authorized_keys. Given that each user logs in with their unique key ...
8
votes
6answers
27k views

How should someone create an encrypted password for /etc/shadow?

I am setting up a new account on a Linux box for Subversion repository access, and can send the password to the new user. However, I think there was a command line utility for this new user to encrypt ...
18
votes
4answers
30k views

Multi-select menu in bash script

I'm a bash newbie but I would like to create a script in which I'd like to allow the user to select multiple options from a list of options. Essentially what I would like is something similar to the ...
18
votes
14answers
39k views

Stop ssh login from printing motd from the client?

I've got SSH passwordless set up, however it prints the MoTD when it logs in. Is there anyway to stop that happening from the client side? I've tried ssh -q but that doesn't work. I don't want to use ...
7
votes
1answer
1k views

Will this HAProxy “restart script” work as gracefully I think it will?

I put this script together from various places. What I am hoping is that it will do the following once run: Pause all "NEW" http traffic for ports 80 and 443 - just "pause" them, don't give any ...
36
votes
3answers
5k views

Run command in bash without save in history

How to run command in bash without saving it in history?
9
votes
3answers
14k views

Linux gzip multiple subdirectories into separate archives?

How would I be able to compress subdirectories into separate archives? Example: directory subdir1 subdir2 Should create subdir1(.tar).gz and subdir2(.tar).gz
16
votes
5answers
20k views

Force SSH to use a specific shell

Is there any way to force SSH to use a particular shell on the remote end, regardless of what the user's default shell is? I've tried solutions akin to: ssh host.domain.com /bin/bash -c ...
15
votes
3answers
2k views

Strange bash history behaviour when running multiple sessions

How is command line history stored when I use multiple terminal windows? I know it is stored in .bash_history but I can't see the logic on what history is used if I open new window. It almost feels ...
13
votes
2answers
7k views

Implementing dry-run in bash scripts

How would one implement a dry-run option in a bash script? I can think of either wrapping every single command in an if and echoing out the command instead of running it if the script is running with ...
10
votes
3answers
12k views

iftop - how to generate text file with its output?

iftop is great tool to view almost live bandwidth usage distinguished by source-ip source-port destination-ip destination port. I'm using it to see which client's ip is using most bandwidth. Now I ...
7
votes
3answers
3k views

Copy a file's owner permissions to group permissions

How can I copy a file's user/owner permissions to it's group permissions? For example if the permissions are 755 I want them to become 775. Clarification: 755 -> 775 123 -> 113 abc -> aac Bonus if ...
3
votes
5answers
5k views

Multithreaded downloading with shell script

Let's say I have a file with lots of URLs and I want to download them in parallel using arbitrary number of processes. How can I do it with bash?
16
votes
2answers
14k views

How do ulimit -n and /proc/sys/fs/file-max differ?

I notice that on a new CentOS image that I just booted up off of EC2 that the ulimit default is 1024 open files, but /proc/sys/fs/file-max is set at 761,408 and I'm wondering how these two limits work ...
11
votes
2answers
3k views

How does the updated Shellshock vulnerability test for CVE-2014-7169 work?

I understand the original test for CVE-2014-6271, which was: $ env x='() { :;}; echo vulnerable' bash -c "echo this is a test" But I'm confused by the updated test and corresponding output for ...
10
votes
3answers
14k views

Start Unix screen, Run command, Detach [duplicate]

How can screen be used to start a new session and run a command within that session without killing that session? screen -S myScreenName runSomething I tried the above command and it says [screen ...
8
votes
7answers
5k views

In *nix, how to determine which filesystem a particular file is on?

In a generic, modern unix environment (say, GNU/Linux, GNU/Solaris, or Mac OS X), is there a good way to determine which mountpoint and filesystem-type a particular absolute file path is on? I ...
5
votes
4answers
3k views

GNU screen loses (parts of) command histories

I use GNU screen with 5 different sessions, each of which stores its own command history. But often I don't find a command in the history, although I'm sure I've used it exactly in the session I'm ...
5
votes
2answers
3k views

Is there a way to configure bash to always page output?

I'd like to configure bash to page the output of all commands. Essentially, I want bash to behave as if every command I enter ended with '| less'. Is this possible?
5
votes
2answers
1k views

What is the purpose of each of the different UNIX/Linux shell startup files?

Previously, when setting up a *NIX environment for the first time, I would put all of my shell customisations into .bashrc, with the following .bash_profile: if [ -f $HOME/.bashrc ]; then . ...
4
votes
3answers
5k views

How can I easily convert HTML special entities from a standard input stream in Linux?

CentOS Is there an easy way to convert HTML special entities from a data stream? I'm passing data to a bash script and sometimes that data includes special entities. For example: "test" ...
2
votes
3answers
1k views

Bash completion dynamic behavior

I would like to have 2 different behavior of "tab" depending of the usage context. I would like to have the default behavior of bind '"\t":complete' any time except when users are trying to complete ...