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

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20
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5answers
938 views

What could make `>` silently fail in Linux?

I ran this command: python ./manage.py dumpdata partyapp.InvitationTemplate > partyapp_dump.json To dump data into the partyapp_dump.json file. But all the data just gets printed on the screen ...
25
votes
7answers
25k views

How to add a timestamp to bash script log?

I have a constantly running script that I output to a log file: script.sh >> /var/log/logfile I'd like to add a timestamp before each line that is appended to the log. Like: Sat Sep 10 ...
3
votes
3answers
3k views

How to delete empty source directories when moving folders with rsync?

rsync can be coaxed into moving folders very similarly and superiorly to traditional mv with the following options: rsync -axvvES --remove-source-files source_directory /destination/ However one ...
15
votes
5answers
12k views

Bash Scripting: Require script to be run as root (or with sudo)

I'm trying to write a bash script (in Ubuntu) that will backup a directory using tar. How can I do a check in the script so that it can only be run as root (or with sudo)? For instance, if a user ...
4
votes
2answers
682 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 ...
3
votes
4answers
2k views

How to get the mount point of flash drive by using uuid?

I am beginner in ubuntu linux and i need to write simple bash script, that can identify necessary flash drive(which contains only one vfat partition) using uuid of this partition, and get the mount ...
-2
votes
1answer
29 views

bash: variable increment does not occur

I have a problem in one of my bash shell scripts. Asked a few colleagues, but they all just shake their heads (after some scratching), so I've come here for an answer. According to my understanding ...
-3
votes
1answer
43 views

Display only some of the lines of the lsof command [closed]

I am trying to create a bash script for displaying only certain lines of the lsof command. I have figured out that the lsof command itself lists information in the form of columns which show info ...
0
votes
1answer
34 views

Logrotate executes postrotate even if file not rotated

I have a problem with my rsyslog and imfile that fails when one of my log file gets truncated.. So to workaround the problem I have modified the logrotate script as follow: ...
2
votes
2answers
70 views

bash: convert date from to unix timestamp changes timestamp

Running the following command at the xen-servers (either DOM0 or DOMU) at $company gives me a negativ number, on every other system zero (0) (even in my cygwin). date -d "1970-01-01T00:00:00" "+%s" ...
31
votes
6answers
20k 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 `-- ...
2
votes
5answers
7k views

shell script: run a batch of N commands in parallel, wait for all to finish, run next N

Task: run blocks consisting of 3-5 commands (in parallel/background). Example block: dd if=/dev/urandom of=/mnt/1/x bs=1024 count=1024000000 & dd if=/dev/urandom of=/mnt/2/x bs=1024 ...
4
votes
3answers
685 views

Is mv with wildcard still atomic

My understanding is that mv dir1/file1 dir2/ is atomic, Is mv dir1/* dir2/ also atomic? As an example, assume there are 10 files in dir1 that are 10GB each.
1
vote
2answers
24 views

How to cp only into the latest directory name?

mkdir test_dir test_dir1 test_dir2 test_dir3 touch file1 file2 file3 cp -v file* test_dir*/ This copies only to test_dir3 and not in test_dir, test_dir1, test_dir2. Why? For that matter it copies ...
-1
votes
1answer
37 views

Bash FTP login into Microsoft FTP Service, Invalid command

This is my script. As you can see it executes only 1 command (cd /) after connecting to a remote FTP server. It's very simple... but it doesn't work and give me "Invalid command". I don't understand ...
12
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 ...
5
votes
4answers
8k views

BASH Scripting, su to www-data for single command

I am working on automating the creation of subversion repositories and associated websites as described in this blog post I wrote. I am running into issues right around the part where I su to the ...
6
votes
1answer
432 views

Bash script parameters

I need to write a bash script, and would like it to parse unordered parameters of the format: scriptname --param1 <string> --param2 <string> --param3 <date> Is there a simple way ...
-1
votes
4answers
158 views

How to test if two given files are identical?

Just updated the code... I get out everytime on the "else" sequence. You can download the update.sh file from my server. it only contains echo "Hallo update" Updated code (03.11.2015) ...
0
votes
1answer
60 views

Straight forward way to run ssh-agent and ssh-add on login via SSH?

I'm trying to have the following commands be auto-executed when I login to my server via ssh: ssh-agent /bin/bash ssh-add ~/.ssh/id_rsa My ssh key has a passphrase and I'm fine with entering it ...
0
votes
2answers
56 views

Bash scripting: Using wildcard

I have two different folders. The first one contains symlbolic links named with the names of my servers (for example: udcedpai101). The second one contains the inventory of my servers where the ...
0
votes
3answers
29 views

bash variables: expanding the values of variables whose names match a pattern

Let's say in bash I have several variables: POD3_1, POD3_A, POD3_2, POD3_B, etc. Each of the variables names begins with "POD3". Let's say I want to expand the value of all the variables on the ...
1
vote
2answers
32 views

Find process with most TCP sockets?

How can I find the process with the most TCP sockets that is currently running with bash ? I would like to only output the process name
14
votes
1answer
13k views

Check if array is empty in Bash

I have an array which gets filled with different error messages as my script runs. I need a way to check if it is empty of not at the end of the script and take a specific action if it is. I have ...
-1
votes
1answer
47 views

understanding the result of this bash script [closed]

I have this simple bash script #!/bin/bash -x for line in `tail /home/user/line` do echo $line done but dont know why it echos all words instead of each line below is output ++ tail ...
-1
votes
1answer
50 views

SED multiline recursive find and replace [duplicate]

I have a large number of sites with the same bit of php inserted in all files that contain footer in their filenames. //###==### malicious code //###==### How to use SED or another command to ...
3
votes
4answers
35 views

Bash evaluation baffling

I'm trying to get a script to do something when one number is bigger than another, in this case, when the system load average exceeds a defined value. All of it is working aside from the evaluation ...
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 ...
1
vote
1answer
35 views

Is using su to drop root in shell scripts a security risk?

When searching for how to drop root permissions in shell scripts, I often see answers using su. However, when you're done using su you can just type logout and be back at the shell of the original ...
0
votes
3answers
55 views

Load users environment variables in a cronjob

How can I load the users environment variables in a cronjob? I have a cronjob which should start a script every minute on my Ubuntu machine: * * * * * /home/user/myscript.sh; In this script I ...
13
votes
7answers
13k 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 ...
1
vote
0answers
26 views

how to filter sar -d disk output tidily

sar -D output-I would like a suitable command to run alongside stress -hdd but this is the output which sar -D 1 10 gives. I have filtered it using both awk |'NR > 1 {printf ...
243
votes
11answers
300k 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 ...
4
votes
1answer
2k views

Using a shell script to check if rsync made any changes

I've got a bash script that rsync's two directories. Sometimes there's a change, odds are there's nothing. I want to run a command only if rsync actually made a change (add/update a file). ...
1
vote
1answer
51 views

How to make a simple script that increases a number character by 1

I have to add a single command for MANY vlans, and wondering if I can generate a simple text file somehow? Then I can simply paste the text file into the network switch and it will add the needed ...
8
votes
2answers
10k views

Writing to stdin of background process

I'm on an Ubuntu 10.04 box, and started a server in the background (myserver &) over ssh. It's been running fine, but I need a way to get at the server's stdin, as the only way to control the ...
1
vote
1answer
41 views

How can I know the absolute path of a running process? on solaris

this is the command to view the process path on Linux ps -auxwe | grep 24466 ( 24466 is only example ) but please advice is it possible to view the path of running process on Solaris if yes ...
0
votes
1answer
20 views

Should I be adding aliases to /etc/profile instead of /etc/basrhc?

I've been adding them to /etc/basrhc, and that works most of the time. But I noticed that when I su to another user, I lose all my aliases. It turns out that /etc/bashrc is only loaded when the ...
5
votes
1answer
1k views

Standard place for user defined bash_completion.d scripts?

I have user access (no root) into a Linux (Suse) machine where I developed some bash scripts and the corresponding bash autocompletion rules. Since the scripts belong only to my user and therefore I ...
6
votes
4answers
7k views

How to parse and convert ini file into bash array variables?

I'm trying to convert an ini file into bash array variables. The sample ini is as below: [foobar] session=foo path=/some/path [barfoo] session=bar path=/some/path so these become: ...
0
votes
1answer
24 views

Resolve packages not found and errors during configure,make,make install in a script

I need to have a script that will install a package from source in a Linux system and need to know how to take care of the errors that usually come up as a result of the first step ./configure maybe a ...
19
votes
8answers
8k views

Is there any reason to use bash over zsh? [closed]

I'm curious about why one would want to run bash instead of zsh. I mean zsh is fully backwards-compatible with bash. Don't get me wrong: I don't dislike bash or anything. I just genuinely want to ...
2
votes
2answers
255 views

Why doesn't this command work as a cronjob, while it works perfectly when typed in a shell? [closed]

If I run this command from the shell, it works as expected: cd ~ && mysqldump --databases --skip-dump-date --host=localhost --user=admin --password=xxxxx --lock-all-tables ...
0
votes
1answer
40 views

Issue with Bash Script On FreeBSD

I have the below bash script set to run every hour via cron as the root user. The purpose of this script is to email us when files have been uploaded to our sftp server and send us the logins. Here is ...
21
votes
6answers
9k views

Can't log in via SSH to any accounts set to use /bin/bash as a default shell

I'm trying to install bash as the default shell on a ARM Linux running on an embedded device (Synology DS212+ NAS). But there's something really wrong, and I can't figure out what it is. Symptoms: ...
0
votes
1answer
90 views

How to automate input for a repetitive script! Expect in Bash?

I am a junior sys admin. Reason I'm asking this question is because we don't have a senior sys-admin here who is proficient with scripting. Senior guys are at the head office and too busy for ...
1
vote
1answer
63 views

Bash: Output of a command is written only to screen and not to another file while using tee, what could be the reason?

In order to troubleshoot some ftp connection error, I've been instructed to write a bash script which will infinitely connect to a remote frp server and get one file from there. ftpuser="ftpuser" ...
1
vote
4answers
2k views

Running ssh-agent from a shell script

I'm trying to create a shell script that, among other things, starts up ssh-agent and adds a private key to the agent. Example: #!/bin/bash # ... ssh-agent $SHELL ssh-add /path/to/key # ... The ...
7
votes
4answers
12k 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 ...
11
votes
2answers
10k 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 ...