Questions specific to GNU’s Bourne Again SHell, as opposed to other Bourne/POSIX shells. For questions about Unix shells in general, use the /shell tag instead.

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4
votes
2answers
343 views

Simple “Variable” Bash File

I just want to make a simple bash file that takes a file name as a parameter. In that bash file, I want to take the name before the extension and have it as a "variable", to use in other places. For ...
1
vote
2answers
799 views

Prepend x/ to line where x is a variable on each line

I want to add $x/ from data formatted as $x-xyz (xyz is a mix of text and number to be ignored). Example data AB-10C CD-02E Output AB/AB-10C CD/CD-02E How do I describe the variable as text ...
3
votes
1answer
34 views

Capture output (sdout/stderr) of SSH port forwarder

I would like to store the error below in a variable: ssh -M -S /invalid/path/forwarder.socket -fnNT -Llocalhost:6301:remote_server:22 proxy_server muxserver_listen bind(): No such file or directory ...
0
votes
3answers
3k views

How to convert Log file to CSV using bash

Is it possible to turn this log entry into a properly formatted csv file using sed/awk? I've tried multiple ways to do this using sed/awk. Alas I couldn't do it. Before I do it in perl. is this ...
7
votes
4answers
127 views

How do I determine if a program is running when I start a shell and start that program if it is not already running?

When I start a shell, in my case bash and/or zsh, what lines do I need to add to .zshrc and/or .bashrc to check to see if a program is already running, and if the program is not already running, start ...
39
votes
5answers
7k views

difference between “function foo() {}” and “foo() {}”

I can define bash functions using or omitting the function keyword. Is there any difference? #!/bin/bash function foo() { echo "foo" } bar() { echo "bar" } foo bar Both calls to functions ...
16
votes
2answers
13k views

Bash: run command2 if command1 fails

I want to do something like this: if cmd1 && cmd2 echo success else echo epic fail fi How should I do it?
8
votes
4answers
20k views

How to check if I can log in to server via ssh?

I have a list of servers: cat list.txt 10.10.10.10 servera 10.11.10.10 serverb How can I check that I can log in via ssh to them or not? I mean by default I should be able to log in via ssh key ...
0
votes
1answer
51 views

Is there a BASH protection on remote copy of root files?

I am trying to use a script to bring back log to the admin. This script is send and load via mussh on the remote machine #!/bin/bash scp files.log user@user:~/ (I have also tried with sudo scp ... ...
2
votes
1answer
52 views

Submit password with sudo and execute script with nohup

I would like to download and run a script in the background so the task is independent of the shell and its exit. Moreover this script should be run as sudo, using: echo MY_PWD | sudo -u MY_USER -S .....
1
vote
1answer
2k views

Changing title without changing prompt on Cygwin

I have the following shell script function from this site that allows me to change the title in both Putty and Cygwin. In Putty connected to a Linux host it changes the title and leaves the prompt as ...
7
votes
2answers
7k views

Can I automate tar's multi-volume-feature?

Ok, so I've just had a read through this page after a way to improve my current backup solution on my Debian server. Tar seems to be offering a quite nice multi-volume feature, although when I try it ...
1
vote
3answers
3k views

Linux: Does find | xargs grep have limitations?

I've historically performed something like: find . 2>/dev/null | xargs grep -i something_to_find 2>/dev/null If my pwd is barfoo (/foo/bar/baz/foofoo/foobar/foobaz/barfoo) it finds matches. ...
18
votes
7answers
1k views

Search for a previous command with the prefix I just typed

We can use up and down arrow to navigate in command history. In some IDE, such as matlab, if we input sth and then press the arrow keys, we stroll among only the history commands starting with what ...
1
vote
3answers
47 views

Multiple logical operators, ((A || B) && C), and “syntax error near unexpected token”

I'm working with Bash 3, and I'm trying to form a conditional. In C/C++, its dead simple: ((A || B) && C). In Bash, its turning out not so (I think the Git authors must have contributed this ...
0
votes
1answer
22 views

how to load a bash alias for graphical terminal emulator

What I'm trying to do: Load an alias The alias: alias notes='cd ~/project/notes' My system: Ubuntu 16.04 and gnome terminal 3.18.3 In my home directory there are the following bash related files: ...
0
votes
3answers
2k views

mailx: nss-config-dir=/etc/pki/nssdb/: No such file or directory

I am trying to send email using mailx using remote SMTP server (in my case it is office365 SMTP Server). Here is the command: # echo "THis is the Body of the email" | mailx -v -s "This is email ...
1
vote
2answers
23 views

Append a “finished” command after a specific command is used

I'm using Bash. I have a build command that I run a few times a day. I also have a command called "beep" that I use to alert me when a command finishes. So normally I do "build arg1 arg2; beep" and it'...
2
votes
1answer
135 views

specify shell for ssh session

I am logging to a remote server via ssh as user www-data. User www-data on the server has his default shell set to /bin/sh, and when I log in, I get dash as my shell. I can then type bash and get bash ...
3
votes
2answers
874 views

Cannot rm file: Disk quota exceeded

In bash (and over ssh) running rm FILENAME gives the error: rm: cannot remove 'FILENAME': Disk quota exceeded. I've seen the other posts (and everyting down the first page of google) on this topic and ...
0
votes
2answers
316 views

Find line within file matching pattern and make a substitution

I'm trying to simplify my life here but I'm stuck. I have a file containing multiple lines. Each line has a user and a number. I'd like to know a bash one-liner to search for a user and change the ...
42
votes
3answers
5k views

How does `yes` write to file so quickly?

Let me give an example: $ timeout 1 yes "GNU" > file1 $ wc -l file1 11504640 file1 $ for ((sec0=`date +%S`;sec<=$(($sec0+5));sec=`date +%S`)); do echo "GNU" >> file2; done $ wc -l ...
13
votes
2answers
42k views

sudo as another user with their environment

$ whoami admin $ sudo -S -u otheruser whoami otheruser $ sudo -S -u otheruser /bin/bash -l -c 'echo $HOME' /home/admin Why isn't $HOME being set to /home/otheruser even though bash is invoked as a ...
1
vote
2answers
69 views

Perl stripping substring with $ in front

I get that perl thinks the part of the string with $ are perl variables. What I'm trying to do with the perl call, is redefine variables preceded by a $ as \$, but that's throwing other errors. I ...
6
votes
2answers
115 views

Notification Listener Behaving Strangely when Backgrounded

I've been struggling to get my IRC-Bouncer/Notification Script working. This is meant to be a script which will automatically login to a remote machine, attach to a screen session (or start one if ...
1
vote
2answers
6k views

how do I run a cron job with a specific user?

My cron and scripting skills are very poor, but I need to run a job every 5 minutes by user 'cpc'. So I created a script and left it at /root. My crontab -e entry about it is: 0-59/5 * * * * /root/...
1
vote
2answers
46 views

Specifying comma-separated command line parameters based on text file lines

I want to run a command like: command argument --parameter=param1,param2,param3 where param1, param2, param3 may be any number of parameters coming from a file params.txt, each on one line. I can ...
11
votes
4answers
10k views

realpath command not found

I have debian squeeze amd64. My current shell is bash. If I write the following in my terminal, it works: $ uname -a Linux core 2.6.32-5-amd64 #1 SMP Fri May 10 08:43:19 UTC 2013 x86_64 GNU/Linux $ ...
3
votes
3answers
37 views

Proper type casting in bash script for use with while loop and modulus

I am trying to write a script to get a random, even hex number. I have found the the openssl command has a convenient option for creating random hex numbers. Unfortunately, I need it to be even and my ...
12
votes
1answer
254 views

Setting temporary bash aliases when entering a folder

Sometimes I like to have very customized bash aliases and maybe keybindings when I enter on a folder (can be a project where I'm used to type lots of commands from CLI). Lets suppose when I enter a ...
1
vote
2answers
46 views

sed: Grabbing and replacing all data between last backslash and a comma

I have data in a csv format that looks like this: F1309-042543,07/14/09 01:39:25,N/A,C:\windows\system32\netsh.exe,N/A,True F1309-042543,11/21/10 03:24:02,N/A,C:\Windows\System32\networkexplorer.dll,...
9
votes
1answer
325 views

Resume a suspended process in a for loop

I am running in bash: for i in ull-*.pbm; do convert $i tmp2/$i.pdf ; done I Ctrl-Z in the middle of running, and then fg its job id. But the remaining iterations do not continue to finish. I ...
0
votes
0answers
20 views

Ensure that file socket is already opened

I'd like to open a simple file socket that can run in background like: nc -l -k -m 10 -U my_socket -c cat & so other processes can connect into it with nc -U my_socket -c read. After this ...
34
votes
13answers
3k views

What is a fast command line way to switch between multiple directories for system administration?

What is a fast command line way to switch between multiple directories for system administration? I mean, I can use pushd . and popd to toggle, but what if I want to store multiples and cycle through ...
1
vote
2answers
47 views

Detect pushd depth in bash?

I would like to be able to programmaticly detect when my pushd stack is non-empty, within a bash shell. Is there any way to detect this? Something akin to $SHLVL would be nice. But so far, the only ...
0
votes
1answer
24 views

Bourne to grep and forward specific text from across a LAN

I'd like to develop a shell that keeps forwarding me the greped text(say compilation errors or warnings, in a single txt output) to some E-mail ID or on some NAS mount point, most importantly from ...
-1
votes
1answer
29 views

How to record numbers of array elements based on selection comparision criteria

I have many files which has many 2x2 arrays. In the present example I show only one file (file1) Input file(file1): 1: 6.1703 541.631 46.0391 2: 6.1930 537.446 45.9239 3: 6.1931 177.171 288.579 ...
0
votes
0answers
40 views

Linux + how to shutdown application properly with reboot or init 0 + init.d scripts

I have Linux Redhat (version 6.5) machine that manages some application before each reboot or init 0 I shutdown the application as the follows: /etc/app-LM.bash /etc/app-UPP.pl /bin/DT-apl.c ...
1
vote
0answers
25 views

Grid Engine for program that needs X11 but doesn't require user input

I have a bash script that calls an executable (some commercial software) in "batch mode". On the commandline, if X is available the program runs to completion and then quits, but if not the program ...
9
votes
11answers
10k views

linux diff tools: create list of modified files

How do I create a list of modified files programmatically using linux command line tools? I'm not interested in the difference in any particular file (delta, patch). I just want to have a list of new ...
1
vote
2answers
45 views

print multiple words seperated by space

I have a text file and the data inside has format like (name age country): michael jordans 25 US adam smith 30 UK chris wood ABC 22 Aus if I use command: cat text.txt | awk {'print $1'} --> it ...
1
vote
2answers
46 views

Alias in bashrc - can't get it to work [closed]

I created a shell script and wish to add it to bashrc. I opened /home/jub/bashrc and added the following to the end of the file: alias myfilesync = './/home/jub/Documents/scripts/myfilesync.sh' Then ...
0
votes
1answer
61 views

Curl a string with whitespaces and characters in it? [duplicate]

I'm trying to create a "simple" script that I'm going to use to create some documentation for Unix/Mac machines. I've successfully received the information I need, but it seems like I can't send it ...
0
votes
0answers
39 views

tailing file in new terminal window

I have the following two bash scripts (perhaps they can be condensed into one). // pre-tail.sh #!/usr/bin/env bash open -b com.apple.terminal `dirname $0`/tail.sh // tail.sh #!/usr/bin/env bash ...
0
votes
3answers
63 views

How do I find the string after a regexp on a single line of text?

I have a text file containing a very long line of JSON data and I need to extract the value of some field.  I realize the easiest way to do this would be to use jq or grep -o; however, I am on a ...
-1
votes
1answer
38 views

Why is `sudo cat /tmp/1 > file` wrong? [duplicate]

I do sudo cat /tmp/1 > /etc/udev/rules.d/69-libmtp.rules but I get bash: /etc/udev/rules.d/69-libmtp.rules: Permission denied System: Ubuntu 16.04 Linux kernel: 4.6
5
votes
2answers
350 views

nested double quotes in highly-voted one-liner

A StackOverflow answer with > 3.5K votes features this one-liner for assigning to DIR the directory of the current bash script: DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )" I'm ...
36
votes
4answers
22k views

How can I delete a word backward at the command line (bash and zsh)?

How can I delete a word backward at the command line? I'm truly used to some editors deleting the last 'word' using Ctrl+Backspace, and I'd like that functionality at the command line too. I am ...
1
vote
1answer
74 views

Killing bash causes it to respawn itself

I'm SSHed into my computer at home and I'm trying to format a drive. lsof /dev/sdb2 shows: COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME bash 1366 mitch cwd DIR 8,18 24576 ...