Questions about bash only, as opposed to other Bourne/POSIX shells. For all Bourne/POSIX-style shells, use the /shell tag instead.

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3
votes
4answers
24k views

Yum update problems on CentOS 6.5 minimal as VMware guest

INFO: I am using Windows 7 Pro (64bit) with VMware Workstation version 10.0.1 . I am using CentOS(64bit) 6.5 minimal, for the first time. I am running this from my workplace network, which may use a ...
2
votes
2answers
201 views

How to prevent screen from terminating once process ends

I'm launching a process in a named screen like: screen -dmS myscreen bash -c "export VAR=123; cd /usr/local/myproject; ./myscript.py" However, after a few minutes, my script crashes and when it ...
14
votes
2answers
33k views

Can I redirect output to a log file and background a process at the same time?

Can I redirect output to a log file and background a process at the same time? In other words, can I do something like this? nohup java -jar myProgram.jar 2>$1 > output.log & Or, is that ...
0
votes
1answer
33 views

error ./c.sh: line 24: [: too many arguments in shell program

I am trying to make a shell script to print the amount of time user was logged into the system but I encountered a too many arguments error. I tried many methods from the internet but none worked. ...
1
vote
1answer
42 views

Issue with ':' character in Bash script over SSH

I am currently writing a script that will perform backups on a set of databases, comress them, encrypt them, transfer them to a separate storage machine, and verify that the file made it successfully. ...
45
votes
6answers
5k views
+200

Can I configure my shell to print STDERR and STDOUT in different colors?

I want to set my terminal up so stderr is printed in a different color than stdout; maybe red. This would make it easier to tell the two apart. Is there a way to configure this in .bashrc? If not, is ...
2
votes
5answers
67 views

bash expanding to same value instead of line by line value in sed command

I have a file containing numbers in it say numbers.txt as follows. 9374541632553 51243747879841 32030098896914 84654557358238 11000656847765 I want to convert it to the following format. ...
1
vote
4answers
54 views

One column into two

I have a file that is one column, and I need to split it into two. Have tried column command and doesn't seem to work: 123-zyx 234-yxw 345-xwv 456-wvu 567-vut 678-uts
208
votes
6answers
84k views

What does env x='() { :;}; command' bash do and why is it insecure?

There is apparently a vulnerability (CVE-2014-6271) in bash: Bash specially crafted environment variables code injection attack I am trying to figure out what is happening, but I'm not entirely sure ...
1
vote
2answers
54 views

What Bash Statement does

Can you explain to me what the below statement does. grep `date +%Y-%m-%d --date='1 day ago'` /path/to/file/FILE_PREFIX_\`date +%Y%m%d --date='1 day ago'`.dsv | grep -v 'ERROR' | cut -d "|" -f 2 | ...
3
votes
3answers
114 views

If statement string comparison

I'm reading a csv file with 14 values per line. I want to convert the HEX value from 10th [f10] value to a DEC value. In order to do this if the 7th [f7] value must hold EnHr or EnSt or SpJb or Chem ...
3
votes
2answers
66 views

Why does man page completion fail after su?

I have a default Debian 8.1 installation. I do su man apt<TAB> but get nothing. I do see the manual when I write man apt-get in both modes: as user mas and as root. However, tab ...
3
votes
5answers
351 views

Bash - Sequence of numbers in the same line

I know the command seq to generate sequence of integers, one per line, but I would like to ask two questions: Is it possible to write the numbers of the sequence in the same line? Is it possible to ...
8
votes
6answers
10k views

Parallelize a Bash FOR Loop

I have been trying to parallelize the following script, specifically each of the three FOR loop instances, using GNU Parallel but haven't been able to. The 4 commands contained within the FOR loop run ...
4
votes
1answer
633 views

KSH styling text based menu using STDERR

Is it possible to format the STDERR in order to have a better looking menu using the select command? I have a simple select select oChoice in $(<tempMenu.menu) ; do case "$oChoice" in ...
1
vote
2answers
56 views

What's the most efficient way to log crontab shell script errors with error occurred time?

A common way to log crontab task errors looks like below: 1 */8 * * * sh /pseudo_path/test.sh 2>> my_err_log It's a concise command, but it can't record the error occurred time, and the path ...
2
votes
2answers
79 views

Bash: Rename file with prefix as suffix

I am trying to do something fairly simple and am a bit unfamiliar with how to accomplish this. I have a set of files that were named: x2_filename.png and would like to transform the file into this ...
0
votes
2answers
36 views

Variable expansion inside parenthesis and quotes

In the script below, I can't seem to make $var1 expand in the second statement. I've tried $var1, ${var1}, echo $var1 and '$var1'. It is inside a few sets of quotes and parenthesis which I guess is ...
0
votes
1answer
27 views

Reload network interfaces without rebooting

I'm doing a BASH script for Arch Linux in a Raspberry Pi 2. The thing is that in some point I'd like to reload the network interfaces without reboot and have my new named network interfaces (en0 and ...
1
vote
2answers
38 views

Best way to make variables local in a source'd bash script?

I have a bash script that generates a report on the progress of some long-running jobs on the machine. Basically, this parent script loops through a list of child scripts (calling them all with ...
1
vote
2answers
37 views

How to number a string in each line of a file

Given file.txt that looks like this: line_ some text line_ some text line_ some text How can I number the lines like this with Bash: line_1 some text line_2 some text line_3 some text Here is my ...
4
votes
2answers
580 views

Passing parsed output of sed to find (in this direction)

Well, I think you can find dozens of questions on this platform how to pipe find output to sed, but I haven't found anything for the reverse direction so far. What I want to do is modify my input, and ...
1
vote
2answers
11 views

How to pass an argument from a bash script to 'x-terminal-emulator -e bash -c'?

Let's say I've got this script : x-terminal-emulator -e bash -c 'echo hello > ~/text' I call it foo.sh and make it executable. If I execute this script I'll have a text file in my home folder ...
10
votes
4answers
1k views

Why does “$(( ~33 ))” produce -34?

$ echo $(( 255 )) 255 $ echo $(( 33 )) 33 $ echo $(( ~33 )) -34 $ echo $(( ~255 )) -256 $ and my kernel is: $ uname -a Linux HOSTNAME 3.2.0-40-generic-pae #64-Ubuntu SMP Mon Mar 25 21:44:41 UTC ...
2
votes
2answers
54 views

Bash script function that changes the value of a variable

I'd like to make a function for a BASH script that changes the value of one of its arguments, that is a variable. The function that I did is: chck_rgx () { # Checks that the given name for a ...
0
votes
1answer
24 views

Sending special characters and new lines via KANNEL

Howto send message to kannel with lines and special character. Example if I have file message.txt which have following text line1 with few special characters like @ " / : line 2 spaces words etc line ...
10
votes
2answers
3k views

Forward SIGTERM to child in Bash

I have a Bash script, which looks similar to this: #!/bin/bash echo "Doing some initial work...."; /bin/start/main/server --nodaemon Now if the bash shell running the script receives a SIGTERM ...
10
votes
7answers
8k views

How to know if /dev/sdX is a connected USB or HDD?

How can I know if /dev/sdX is a local HDD or usb key ? best doing this without root privileges. OK , udevadm helped a lot: For local HDD: udevadm info --query=all --name=sdb | grep ID_BUS E: ...
3
votes
1answer
21 views

Bash script with conf file with unknown number of sets of variables

I am writing a bash script that has a configuration file. The configuration file will have sets of mode and mtu values. There can be zero or as many sets as the user defines. The bash script will ...
0
votes
4answers
150 views

Where is .bashrc file found in Linux?

I am not finding my .bash_login and .bash_profile root@linux:~# locate .bash* /etc/bash.bashrc /etc/skel/.bashrc /etc/skel/.bashrc.original /home/noroot/.bashrc /home/noroot/.bashrc.original ...
1
vote
2answers
43 views

Grep and ignoring leading whitespace

I've been working on a bash script to search for names of defines, and then grab the hex values for them and put them in the list. Once I have the list of names I'll attempt to search for "#define ...
1
vote
1answer
19 views

Arrange program windows out of bash script?

I'm writing a shell script to automatically launch my work environment. It would be pretty nice to arrange the program windows automatically (for example vim opens at the left on desktop, and browser ...
0
votes
0answers
32 views

Drawing a histogram from a bash command output

I have the following output from a miRNA Predictor: Read Sequence:hsa-miR-576-3p MIMAT0004796 (22 nt) Read Sequence:gi|182396|gb|M74088.1|HUMFAPAPC Human APC gene mRNA, complete cds (8972 nt) ...
1
vote
1answer
25 views

Calculate Out data Kb/s for specific PID

I have this command cat /proc/8221/net/netstat | grep 'IpExt: ' | tail -n 1 | awk '{ print $9 }' This shows me out bytes in that moment right? If yes, how can i show total kb/s in just one command ...
1
vote
3answers
34 views

bc scale: How to avoid rounding? (Calculate small binomial probability)

Following code calculates the Binomial Probability of a success event k out of n trials: n=144 prob=$(echo "0.0139" | bc) echo -e "Enter no.:" read passedno k=$passedno nCk2() { num=1 ...
37
votes
4answers
12k views

What is the purpose of the hash command?

If you run hash it shows the path of all commands run since the hash was last reset (hash -r) [root@c04c ~]# hash hash: hash table empty [root@c04c ~]# whoami root [root@c04c ~]# hash hits ...
15
votes
3answers
3k views

What does “rm is hashed” mean?

I'm going through http://mywiki.wooledge.org/BashGuide/CommandsAndArguments and came across this: $ type rm rm is hashed (/bin/rm) $ type cd cd is a shell builtin Just a little earlier, the guide ...
0
votes
0answers
29 views

How to scan for wireless networks fast

I have written a script which scans for wifi networks with iw dev wlan0 scan and put the SSIDs in a file. Is there a similar tool wich works a bit faster?
0
votes
1answer
27 views

How to copy files to the timestamp generated directory?

Hello I am trying to copy all files from Documents directory to the backup directory that has a timestamp. So I have created a directory called bk$( the time stamp of the directory) and I am trying to ...
7
votes
1answer
654 views

How does VARIABLE=() { function definition } work in bash

I have seen something like this in my bash ENV: module=() { eval `/usr/bin/modulecmd bash $*` } How does this construct work? What is it called? I'm not asking about modulecmd, I am asking about ...
2
votes
3answers
233 views

How to 'drop'/delete characters from in front of a string?

I have a string that I would like to manipulate. The string is H08W2345678 how would I be able to manipulate it so the output is just W2345678? Similarly if the I wanted to drop the last 4 ...
0
votes
1answer
10 views

Command Run Differently Depending on How Logged In?

Is there a way to have one command run differently, depending on the manner in which one is logged into the session launching it? Basically, we have a command that when run, launches vim to display ...
1
vote
2answers
86 views

How to while read line with a pipe

I am currently trying read a csv file with BASH. The 10th [$f10] value of the csv file must be greater then 0 for a given machine class and machine ID [m_class] and [m_id] (these are user defined) . ...
3
votes
1answer
305 views

Add 30 days in date

Using bash or mysql , how can I add 30 days in user expiry table? Example I have DB name USERS and table expiry like this: USERNAME EXPIRATION JOHN 2015-09-26 I want the command to take ...
4
votes
2answers
340 views

Disable bash's cache of executables in the path

Note that this is not a duplicate. I am asking about disabling the cache, not clearing it. If you have a cache to clear, then it is obviously not disabled. On the rare occasions that I notice bash's ...
1
vote
4answers
102 views

How to use regex in sed?

I need to revoke the sudo access to the user using sed in scripts. I want to comment the user only if the line contains /bin/su - root Let us consider the file as below, in which I have to comment ...
2
votes
2answers
44 views

find closest matching folder

What is the best way to sort the results of $ find . -name scripts -type d by the occurrences of '/' and then choose the first result. I want to create a function that would cd down to a common ...
2
votes
2answers
19 views

Is there a way to colorize output per stream from a program [duplicate]

I'm looking for a method to have bash colorize the output from a command based on what stream it was written to the terminal from. Is there any way to get it to colorize per stream? Like for example ...
1
vote
1answer
29 views

Get value of environment variable in for loop

I have several environment variable pam_branch app_branch worker_branch I use an array to define different projects and I want to get the values of these env var by rebuilding them in a for loop ...
2
votes
3answers
176 views

copy from file and paste in the terminal without x server

I have got an ubuntu linux without x server installed on it (cos it's only a gateway). I am requested by an application (ossec,-my question is not ossec related-) to paste information into the ...