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

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140
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39answers
36k views

What useful things can one add to one's .bashrc? [closed]

Is there anything that you can't live without and will make my life SO much easier? Here are some that I use ('diskspace' & 'folders' are particularly handy). # some more ls aliases alias ll='ls ...
12
votes
5answers
4k views

Log all commands run by admins on production servers

It is company policy for admins to login to the servers via a personal username, and then run sudo -i to become root. Upon running sudo -i, sudo will create an environmental variable called ...
11
votes
6answers
8k views

How can I determine what is taking up so much space?

I was using df -h to print out human readable disk usage. I would like to figure out what is taking up so much space. For instance, is there a way to pipe this command so that it prints out files that ...
214
votes
33answers
72k views

How can I sort du -h output by size

I need to get a list of human readable du output. However, du does not have a "sort by size" option, and piping to "sort" doesn't work with the human readable flag. For example, running: du | sort ...
84
votes
9answers
20k views

Keeping a linux process running after I logout

I'm connecting to a linux machine through SSH, because I'm trying to run a heavy bash script that makes filesystem operations, and it's expected to keep running for hours. But I cannot leave the SSH ...
12
votes
3answers
4k views

Do background processes get a SIGHUP when logging off?

This is a followup to this question. I've run some more tests; looks like it really doesn't matter if this is done at the physical console or via SSH, neither does this happen only with SCP; I also ...
6
votes
2answers
1k views

My cron tasks report command not found [duplicate]

This is the contents of my crontab file: 0 0,6,12,18 * * * cd /var/www/app/current && backup perform --trigger db_backup --config_file config/backup.rb --data-path db --log-path log ...
4
votes
2answers
246 views

Repartitioning two disks without a loss of data

I am interning at a software company and I have hit somewhat of a brick wall. Here is the deal: The Problem: We have some boxes around here that were incorrectly partitioned for 2 x 500 GB drives. ...
21
votes
5answers
2k views

Avoid to keep command in history

I use bash and I would like to avoid some commands being kept in the history. Is it possible to do that for the next command only? Is it possible to do that for the entire session?
13
votes
2answers
2k views

What is the difference between sudo -i and sudo su -

What is the difference between commands sudo -i and sudo su -? Are they the same?
9
votes
3answers
2k views

Logging a “persons” activity in Linux

So I've read many of the posts related to this and have just come up more confused than before. There are recommendations for various tools including ttyrec, snoopy, acct, rootsh, sudosh, ttyrpld, ...
5
votes
2answers
4k views

No TTY present when running commands over SSH in here-document

I'm trying to run a command over SSH like this in a here-document: ssh example.com <<END sudo /etc/init.d/apache2 reload END Which normally works except when I'm trying to run something that ...
4
votes
1answer
655 views

Undoing chmod 777

Sometimes in desperation, to test if my problem is not the permission problem I do: sudo chmod -R 777 mydir/ In most cases it does not helps, and now I have two problems ;) Files inside mydir/ had ...
3
votes
3answers
3k views

How can I display the IP address of an interface?

If I want to display the IP address that is assigned to eth1, how can I do this in Bash?
0
votes
1answer
199 views

How do I rename all files index.php containing a certain folder in the path?

I want to rename all wordpress admin index files into index_disabled in the folder /var/www/ I need a script like find /var/www/ -path '*wp-admin/index.php' -exec mv {} $(dirname ...
175
votes
11answers
200k views

How to determine if a bash variable is empty?

What is the best way to determine if a variable in bash contains ""? I have heard it recommended that I do if [ "x$variable" = "x" ] Is that the correct way? (there must be something more ...
99
votes
3answers
34k views

What is the difference between double and single square brackets in bash?

I just wondered what exactly the difference between [[ $STRING != foo ]] and [ $STRING != foo ] is, apart from that the latter is posix-compliant, found in sh and the former is an extension ...
13
votes
6answers
12k views

How do I run a local bash script on remote machines via ssh?

I am looking for a way to push configuration from one central machine to several remote machines without the need to install anything on the remote machines. The aim is to do something like you ...
15
votes
6answers
14k views

If I launch a background process and then log out, will it continue to run?

Asking this after a prolonged discussion with a coworker, I'd really like a clarification here. I launch a background process, either by appending "&" to the command line or by stopping it with ...
15
votes
6answers
135k views

How to pass password to scp command used in bash script? [duplicate]

Possible Duplicate: Connect through SSH and type in password automatically, without using a public key I have a bash script that makes dump of DB then copies file from one server to another ...
4
votes
2answers
3k views

ssh fails to execute remote command when run from cron bash script - works from CLI

I have a script, written in bash, which runs from cron. One of the first things it does is SSH to a remote host and retrieve a list of files in a directory. Everything works fine when run from the ...
17
votes
1answer
949 views

Shell command slow when using pipe, fast with intermediate file

Does anyone understand this huge difference in processing time, when using an intermediate file, or when using a pipe? I'm converting tiff to pdf using standard tools on a fresh debian squeeze server. ...
8
votes
1answer
625 views

Is it possible to hide a malicious alias in Bash on Linux?

Is it possible to conceal the existence of a malicious alias in Bash on a Linux system and have it executed by the user without their knowledge?
6
votes
3answers
5k views

Rsync seems incompatible with .bashrc (causes “is your shell clean?”)

It turns out rsync can't work with a remote server which has a .bashrc file? At local client i got when run rsync: protocol version mismatch -- is your shell clean? (see the rsync man page for an ...
6
votes
2answers
7k views

How to repeatedly call rsync until files are sucessfully transferred

I'm trying to syncronize files from a remote server that is not reliable, meaning the connection tends to fail "randomly" with rsync: connection unexpectedly closed Rsync is called with ...
6
votes
3answers
10k views

kill a screen (but not all screens)

I have multiple screens running on an Ubuntu server that are initiated as: screen -dmS screen1 cmd screen -dmS screen2 cmd etc... And I need to kill one screen, but not all of them. What is the ...
4
votes
3answers
1k views

SSH from A through B to C, using private key on B

I'm looking for a simple way to SSH from my local machine, A, through a proxy, B, to a destination host, C. The private key that goes with the public key on C is on B, and I can't put that key on my ...
3
votes
3answers
3k views

How To Search authorized_keys For Public Key And Remove It

Hello I am looking for assistance searching /root/.ssh/authorized_keys for a given public key (call it $pub_key) and removing it. Want to do this in bash script. What's the best way to accomplish ...
3
votes
3answers
3k 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 ...
0
votes
2answers
3k views

“Corrupted MAC on input. Packet Corrupt” on file transfer over SSH, SCP, and FTP on Linux Server

help on this would be great. Specs: LAMP server Linux OS - Debian 5.0.1 4x Intel(R) Xeon(TM) CPU 2.80GHz Important Packages: openssl - SSL security iptables - firewall to block all requests ...
5
votes
6answers
2k views

What does passing the -xe parameters to /bin/bash do

Exactly what the title says. I'm not having much luck finding the proper documentation to see what -xe does in the following use case: #!/bin/bash -xe what do those parameters do and where it is ...
2
votes
4answers
5k views

Why does the $PATH of an ssh remote command differ from that of an interactive shell?

I have a user that has made no modifications to the $PATH in any dot-files: it is exactly the system default setting. From a login shell: $ ssh example.com user@example.com:~$ cat /tmp/hello.hs ...
2
votes
4answers
256 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
3answers
3k 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 ...
6
votes
4answers
6k 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.
4
votes
1answer
808 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 ...
3
votes
2answers
2k views

How to keep: daily backups for a week, weekly for a month, monthly for a year, and yearly after that

I need to backup data and config files on this server, daily. I need to keep: daily backups for a week weekly backups for a month monthly backups for a year yearly backups after that All of this ...
3
votes
5answers
758 views

Difference of running scripts manually or with a cronjob

I have a PHP script that I want to run every 10 minutes, going through database records and creating/editing movies through MEncoder. I've set up cron job to accomplish this, but it doesn't work very ...
2
votes
1answer
256 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
104 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
678 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
2k 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 ...
87
votes
24answers
25k 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 ...
27
votes
6answers
18k 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 `-- ...
34
votes
3answers
9k views

.profile vs. .bash_profile vs. .bashrc

what are the functional differences between these guys?
34
votes
1answer
6k 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 ...
26
votes
8answers
20k 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.
7
votes
6answers
6k 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 ...
8
votes
4answers
30k 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 ...
11
votes
14answers
22k 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 ...