The shell is unix's command-line interface. You can type commands in a shell interactively, or write scripts to automate tasks. Use this tag for questions applying to /bin/sh and most compatible shells (ash, bash, ksh, zsh, …).

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95 views

Peculiar Solaris integer comparison behaviour

This one caught me unawares! We have a Solaris machine (version: SunOS 5.8) hosting a pivotal script/process which has been running for many years without complaint. We recently had cause to have a ...
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218 views

How do I execute in background / return early?

For reference, I'm using phpseclib to control a remote SSH server using the 'root' account. I have to start/stop a java process which is ran in the background. Stopping works fine with killall java ...
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112 views

What default shell to use for an SSH user limited to a single command

When limiting a user to a single command via ssh, what default shell should be used for the user? This is a follow up to how can shellshock be exploited over SSH? I have a machine that is running an ...
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53 views

Where EOF character is processed when it sent over telnet connection

Lets suppose I am connecting to telnet server, where bash is running. I am executing comand "cat > /tmp/qqq"; typing some contents of a file and finally sending 0x0a 0x04 which meant EOF. The ...
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68 views

List all btrfs filesystems and subvolumes in shell

Is there a convenient way to get information on all btrfs filesystems subvolumes without resorting to C, i.e. in POSIX shell ? /sys/fs/btrfs contains info only on filesystems, nothing on subvolumes, ...
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53 views

Higher-level wrapper for entr or inotifywait

I'm looking for a way to rerun a specific command as soon as any of the files in a subdirectory (perhaps minus selected excludes) changes. Use case I'm working on a project that is self-contained in ...
2
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0answers
61 views

A way to distinguish between interleaved output from two background processes

If I have two backgrounded processes that produce input to STDOUT or STDERR (e.g., two installation scripts), is there an easy way to make these two output streams distinguishable? I guess I can pipe ...
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89 views

“Restart” a process in the same terminal?

I put "restart" in quotes because the following question on SO illustrates what I'm trying to do: http://stackoverflow.com/questions/27957091/restarting-a-process-in-the-same-linux-terminal I'm ...
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50 views

How to get the mplayer's single-line playing progress info?

mplayer shows and refreshes a single-line playing progress when playing a media file. A sample result is: A: 17.2 (17.2) of 213.0 (03:33.0) 0.5% And I'm trying to grep this playing progress and ...
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63 views

Is there a difference between double quoting a variable or a whole line in echo

When you type, for example, echo Variable "$var" is not initialised. and echo "Variable $var is not initialised." the front end result is the exact same (as far as I know, at least). But I was ...
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82 views

Read output in `screen` from outside

Suppose I opened up a screen to run some program that outouts some result. Once the program finishes, is there a way to get the result in the screen from outside. For example: I opened up a screen ...
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110 views

How can you get the current terminal line (the one that is still editable by the user)?

I need a way to use the current line which the users typed into as variable for a shell function. my current code, which can be called by ctrl+r zle -N search bindkey "^R" search search () { read ...
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315 views

How to pass multiple commands via pssh and multiple xterms

I'm attempting to open multiple xterms and run a command as an SAP user via sudo using pssh. So far, I'm able to run PSSH to a file of servers with no check for keys, open every xterm in the servers ...
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401 views

How does SELinux / SEAndroid prevent or allow pseudo terminal allocation?

I'm trying to resolve an SSH connection issue on an Android phone running SELinux in "Enforcing" mode. The problem is that any SSH connection that tries to allocate a pseudo-terminal (/dev/pts etc) is ...
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109 views

Segmentation fault with dialog

I'm getting a segmentation fault with the following script when it's more that one child dir past the pwd. The program kills with the error message and I have to reset the shell. For example: I start ...
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138 views

zsh: Echoing every statement?

I have an odd problem with zsh when I switch between shells in a particular way: Option 1 (works well): I start a zsh shell. I switch to tcsh with /bin/tcsh, and I switch back to zsh with /bin/zsh ...
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355 views

What happens when you background a function which calls another function?

Question says it all on the tin. Can someone explain to me what goes on here ? I'm trying to find out how to background a process in a script that calls another function and reliably terminate it when ...
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30 views

XZ - Cannot allocate memory

If i run this command: XZ_OPT=-9 tar --xz -cvf files/compressed/xz/archive.tar.xz -C files/original/ . Get this message: xz: (stdin): Cannot allocate memory tar: ...
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30 views

initramfs-tools syntax errors with Heirloom sh

My current system is: $ lsb_release -a No LSB modules are available. Distributor ID: Debian Description: Debian GNU/Linux 8.1 (jessie) Release: 8.1 Codename: jessie with kernel: $ uname -a ...
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32 views

csh: How to save the shell environment (env, current dir, shell history) in a file and set it on another shell?

I start interactive terminal using farm (LSF). These terminals get opened on some random host and get closed automatically after 15 days. I want to save the current shell environment (env, current ...
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69 views

Easy way to compare BIOS information between two machines?

I have two machines - machineA and machineB running Ubuntu 12.04 Is there any easy way I can compare BIOS settings between those two machine and see the difference instead of doing it manually using ...
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27 views

Is it possible to create aliases that affect services starting?

Currently I have a custom service that executes java in multiple places. I want to be able to add an option to any executions of java this service will spawn (I'm specifying the error log location, ...
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73 views

Shell Script to change user shell

I am writing a script that would be invoked to change user shell. The basic requirement is that once user gets authenticated (e.g: thorough some web application) the script would be invoked to set the ...
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39 views

Setting custom baud rate on console

Just for aesthetics I would like to have my text on my console be displayed at a lower speed. I've tried using things like screen with custom baud rates of /dev/tty1 but it wouldn't work, input from ...
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86 views

Sed regex printing into a file.txt

I'm connected to a MQTT stream, and I filter out the data by entering : mosquitto_sub -d -t +/# 2>&1 | sed -n "/PUBLISH/{s|.*\('.*',\).*|\1$(date),|;N;s/\n//;p}" into the Ubuntu terminal. ...
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84 views

What is the meaning of the string **/* when used with grep?

I came across this picture (below), obviously it is a pun or some kind of allusion incorporating command-line expressions. Frankly speaking I do not understand anything of it except for grep -n. ...
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82 views

gdrive -bash: /usr/bin/drive: cannot execute binary file

I am processing hundreds of image files on a weekly basis and gdrive would be perfect for automatically making duplicate copies of the raw images for archive before the originals go through the ...
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30 views

optimisation of bash globs

Looking for a guide to optimising regexp matches in bash. I have a script that loops over a very long list of URLs looking for patterns. Currently it looks a little like the fragment below. Is there ...
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101 views

pkill -P $ID working while kill — -$ID not

I was playing around with creating and killing process groups on linux ( ubuntu ) I am trying to kill a process group and am being driven crazy by the fact that pkill -P $ID works while kill -- -$ID ...
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516 views

Cannot add startup service to openWRT from init.d

I have openWrt installed on a TP-Link TL-WA901N/ND v3. I don't have luci package installed because I don't have enough space, so I can only do thing via cli. What I'm trying to achieve is to create a ...
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303 views

Cannot SSH after switching to Netgear router

I have Comcast Xfinity internet. When I was sent their Wifi router/Cable modem combo box, I was able to use SSH perfectly. However, since the Wifi from the box was weak, I decided to buy my own ...
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761 views

Load a background image or set the background color if Konsole/Shell is running SSH

I want to set my laptop to load an image in the shell's background or set the background color to red if I'm connected via SSH. How can this be done? With a bash function in .bashrc? I have: Set the ...
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221 views

How to start a process chain from the shell

Is it possible and if so how do I: Start a /bin/bash process that is not bound to a terminal from a terminal? Hence, a shell process that shows up in the process tree as init -- bash. (Shells ...
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143 views

Chrome OS: Crosh Window and Hostname

I have a couple of questions regarding Chrome OS: By default Ctrl+Alt+T opens a crosh window within the Chrome browser. I have the Crosh Window extension, which I would like Ctrl+Alt+T bound to - ...
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208 views

Measuring context switches of a LWP gives incorrect results. Why?

I have a Java thread pinned at my cpu core. It is busy spinning and I see through top that it is running fine: %Cpu0 : 0.0 us, 0.0 sy, 0.0 ni,100.0 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st %Cpu1 : ...
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102 views

Execute commands on TMUX Detach

Is it possible to execute commands on tmux detach? I usually have a rails console and server running in the tmux session, on detach is it possible to automatically end those? Thanks.
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59 views

Merge several files with maximum 1 line difference

Suppose I have the following files: file0.c: int b=NULL; int a=NULL; file1.c: int b; int a=NULL; file2.c: int b; int a=NULL; I am looking to merge the files file1 and file2 to generate the ...
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477 views

Using node.js and shelljs as interactive shell

Following the answer given at unix.stackexchange.com/questions/58011/is-there-a-javascript-shell That requires me to always execute var shell=require("/usr/local/lib/node_modules/shelljs"); It ...
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274 views

Serial Communication on DD-WRT stty config not sticking

I am attempting to control a serial device (in this case a projector) using a Fonera router with DD-WRT on it. I've got the serial port on the fonera wired through a level shifter and then into my ...
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0answers
382 views

gnome-terminal cmd leaving processes open after closing parent window

The following simple command should demonstrate my issue: gnome-terminal --tab -t "Tab 1" -e "/bin/bash" --tab -t "Tab 2" -e "/bin/bash" This should open a new window with two tabs and an active ...
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741 views

service command: Failed to issue method call

I downloaded the source of tinyproxy and then use ./configure make make install to install it Then I want to start it, but get errors, like the following: [root@kitty tinyproxy-1.8.3]# service ...
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96 views

add audio from playing file to microphone stream

I need to add a sound to what the microphone is capturing, is it possible? I started with man aplay and found that I can do aplay -D PCMdevice filepath.wav so then I listed the PCM devices with ...
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0answers
33 views

Make zkbd ignore $DISPLAY

Is it possible to make zkbd ignore $DISPLAY variable? I have set up when I log in to different X sessions and it is annoying if suddenly I need to reenter/copy configuration (and I have no idea why ...
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0answers
168 views

(KDE or X ) Script opens konsole in wrong virtual desktop

I have this script. I put it in ~/Desktop. I view the script on my desktop in a "Folder View" widget. When I click on the script, I get list of users, then I get an authorization dialog box ( for a ...
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522 views

Manually setting environment variables for Metasploit

How do I set manually environment variables for Metasploit, when I execute db_driver I get this message: [*] No Active Driver [*] Available: [*] DB Support: Enable the postgresql driver ...
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18 views

Why won't MOTD display output from a Python script it calls outside of /etc/update-motd.d/ unless it's in this directory?

The Situation We're running a headless Ubuntu 14.10 Server to fulfill various needs and tests. I was experimenting with changing the MOTD for SSH sessions via /etc/update-motd.d/ so as to display ...
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18 views

display JPEG Exif header with od (Octal Dump)

there are several command line tools to show Exif header of JPEG images. I wish to see the same info with od (octal dump) $ jhead 1430472877538-0.jpg File name : 1430472877538-0.jpg File size ...
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0answers
22 views

Why rsyslog leaves the last file in spool directory

Suppose I am using a rsyslog remote server (R1) & have a client box (C1). C1 is configured to sync up and use R1 for logging (over port 514; TCP) The spool directory is '/var/log/rsyslog'. Now, ...
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0answers
30 views

what is scriptname TODAY 0 mean in crontab?

We have some scripts scheduled in crontab with TODAY 0 or YESTERDAY 0 after the script name. What does they mean?
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26 views

Why does the Gnome desktop (nautilus) and the user's shell script conflict?

Why is that if the user's shell isn't defined to be /bin/bash but a custom bin/bash type script instead the graphical interface's desktop part will load slower or over vnc it won't load at all just ...