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

learn more… | top users | synonyms (1)

1
vote
1answer
115 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
924 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
3k 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 ...
102
votes
26answers
32k views

How do I prevent accidental rm -rf /*?

I just ran rm -rf /* accidentally, but I meant rm -rf ./* (notice the star after the slash). alias rm='rm -i' and --preserve-root by default didn't save me, so are there any automatic safeguards for ...
37
votes
8answers
12k 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 ...
43
votes
12answers
60k 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 ...
31
votes
6answers
19k 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 `-- ...
41
votes
3answers
14k views

.profile vs. .bash_profile vs. .bashrc

what are the functional differences between these guys?
18
votes
6answers
57k 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 ...
30
votes
8answers
31k 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.
34
votes
1answer
8k 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 ...
21
votes
4answers
18k 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. ...
14
votes
7answers
10k 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
7k 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 ...
7
votes
6answers
22k 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 ...
12
votes
1answer
473 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 ...
32
votes
3answers
4k views

Run command in bash without save in history

How to run command in bash without saving it in history?
17
votes
2answers
13k 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?
13
votes
13answers
29k 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 ...
12
votes
4answers
19k 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 ...
6
votes
1answer
745 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 ...
27
votes
5answers
21k views

What is “-bash: !”: event not found"

Try executing the following under a bash shell echo "Reboot your instance!" On my installation: root@domU-12-31-39-04-11-83:/usr/local/bin# bash --version GNU bash, version 4.1.5(1)-release ...
14
votes
4answers
4k 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; ...
14
votes
3answers
1k 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 ...
9
votes
1answer
1k views

Where is $BASH_ENV usually set?

I have twin Linux servers that should be configured identically, however ssh commands to one of them are failing for commands that require a path that's specified in ~/.bashrc. For example, I can use ...
5
votes
7answers
23k views

script to automatically test if a web site is available

I'm a lone web developer with my own Centos VPS hosting a few small web sites for my clients. Today I discovered my httpd service had stopped (for no apparent reason - but that's another thread). I ...
11
votes
5answers
32k views

Determine if filesystem or partition is mounted RO or RW via Bash Script?

Is there an easy way to determine if a mounted filesystem is mounted as Read-Only or Read-Write? I was thinking just to pipe mount but I thought there might be an easier way.
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
2k 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
944 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 . ...
3
votes
5answers
3k 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?
2
votes
3answers
913 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 ...
8
votes
2answers
4k views

Start Unix screen, Run command, Detach

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 ...
7
votes
7answers
4k 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
1answer
612 views

how to pre-create directories on linux for file storage

looking for a way to pre-create directories on linux to be used to store a large number of files. We will be generating file ids using a GUID - I need to keep a copy of these files on a linux web ...
5
votes
8answers
3k views

Bash can't start a programme that's there and has all the right permissions

This is a gentoo server. There's a programme prog that can't execute. (Yes the execute permission is set) About the file $ ls prog $ ./prog bash: ./prog: No such file or directory $ file prog prog: ...
4
votes
5answers
1k views

Bash: Quotes getting stripped when a command is passed as argument to a function

I am trying to implement a dry run kind of mechanism for my script and facing the issue of quotes getting stripped off when a command is passed as an argument to a function and resulting in unexpected ...
3
votes
3answers
2k 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" ...
3
votes
2answers
225 views

Writing an SVN hook that updates copy of committed code

I have a SVN repository with a lot of sub-projects stored in it. Right now in my post-commit I just loop through all possible folders on the machine and run svn update on each: REPOS="$1" REV="$2" ...
1
vote
3answers
4k views

Appending a line to a file if it doesn't exist using Puppet

I've got a defined resource type to append a line to a file if it doesn't exist, as per below: define appendLineToFile($file, $line, $user) { exec { "echo \"\\n$line\" >> \"$file\"": ...
1
vote
3answers
1k views

Run FTP session from bash script

I'm trying to write a BASH script to test if an FTP site that I own is running. I therefore want the bash script to connect to the FTP site, log in with a dummy account and redirect the output to a ...
0
votes
1answer
451 views

Disable the ability to hide bash command history

User can hide the command history in bash by either append a space before the command unset HISTFILE How to disable this?
0
votes
2answers
3k views

Editing .bash_profile file not taking effect

I need to put export PATH=$PATH:/opt/lampp/bin to my ~/.bash_profile file so that mysql from command line works on my system. Please check mysql command line not working for further details on that. ...
14
votes
17answers
43k views

Shell Command for Getting IP Address?

Is there a bash command to find the IP address for an Ubuntu box? I need to find the IP address so I can ssh into the machine later.
13
votes
5answers
11k 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 ...
6
votes
6answers
11k views

What is a recommended way to patch the Shellshock Bash bug on an unsupported Ubuntu server?

I maintain an out-of-support Ubuntu 12.10 (Quantal Quetzal) server (don't ask me why, please), and we need to patch the Shellshock Bash security bug. As upgrades are not available anymore, what ...
6
votes
1answer
468 views

Providing normal users(non-root) with initialization and shutdown auto-run capabilities

I'm hosting an experimental/testing Linux box, running Debian Wheezy 7.4.0 distribution. Different users log into the machine over ssh to their accounts and are allowed to run the development tools ...
5
votes
2answers
982 views

How can I make bash to log shell commands to syslog?

Bash 4.1 is able to log the history to syslog. However I can't seem to make it work under FreeBSD 8. I've tried re-compiling bash from ports with -DWITH_SYSLOG= but to no avail. Has anyone managed to ...
5
votes
2answers
1k views

Bash: menu-complete only for few matches

With Bash auto-completion, is there a way to cycle through matches using menu-complete only if there are 1-2 options, and use listing with complete otherwise? Example home directory contains ...
4
votes
2answers
699 views

rsync not removing single quotes around array of strings --filter list

Trying to safely retrieve files from heavily infected Windows XP and 2003 machines that came to us from an acquisition. I have a similar need for automating a script that would run on PXE booted ...