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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57 views

Why does OS X `install` errors on redirected input when the same version of `install` on linux works fine?

I would like to use install command in order to create a new executable file with pre-populated content (e.g. with single pwd command in it). So I've extended this example which creates a new empty ...
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302 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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58 views

Shell Arithmetic Expansion with Quotes

In Bash and Dash, using quotes in an Arithmetic Expansion is illegal: $ bash -c 'x=123;echo $(("$x"))' bash: "123": syntax error: operand expected (error token is ""123"") $ dash -c 'x=123;echo ...
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50 views

cursor and combining diacritics in shell

I frequently deal with combining diacritics, especially the combining acute accent (U0301, or \xcc\x81). I have a keyboard set up to insert this character, and that works fine in the shell. $ echo а́ ...
3
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176 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, ...
3
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168 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 ...
2
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201 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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103 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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110 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 ...
2
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118 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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67 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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71 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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112 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 ...
2
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136 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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501 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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522 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 ...
2
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141 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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484 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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154 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 ...
2
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0answers
36 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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500 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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50 views

Some commands are no longer responding?

I have a Debian based distribution & lately a problem has been encountered when trying to execute the gcc or man command's (And probably other commands I haven't found yet). When I type them in ...
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17 views

How to switch to another screen to run git commands while resolving conflicts (blocking command)?

Often times, I work out of a single shell when I run git commands. For example, I will start a merge: $ git merge origin/master If during this merge there are conflicts, git will "block" the shell ...
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51 views

File exists but errors with “mv: cannot stat: No such file or directory”

For some reason my script cannot copy or move files that exist. It comes up with the errors below. Can someone tell me why? cp: cannot stat '/mnt/sd/bbu/install/scratch/bin/.': No such file or ...
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15 views

Schedule (Cron) executing tasks based on bash scripts using CronniX

I'm still quite new you Mac and OS X but do have some background about other UNIX based systems, so please excuse for any misunderstandings. My goal is to implement a function that executes certain ...
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23 views

Start a subshell then run commands

Say I have a script that is always run from an interactive shell. I would like this script to launch an interactive subshell that is a replica of the parent (i.e., all environment variables, etc. ...
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27 views

'Chain' shells' profile and runcom files?

While setting zsh up, I found a post stating that to keep a .zshrc as clean and backwards compatible as possible, one can 'chain' the shells' configuration files. If I recall, it consists more or less ...
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40 views

Removing duplicates in a large text list

I've searched around the internet and stackexchange for this. Even though there are lots of similar topics, I haven't found a solution yet. So, I have a quite large list (approx. 20GB), which ...
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97 views

unix chroot jail shell (with or without sudo?)

at the moment I am creating a chroot jail. Therefore I read some articles and everything seems to be clear, exept for one thing: the chroot jail shell In one source they created the following setup ...
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28 views

tab-delimiting a file in shell

I have a file that I want to put in a table in SQL with 10 columns. I am trying to tab-delimit the file so that the file can go in the table. Here is part of my txt file: Chr12 MSU_osa1r7 exon ...
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36 views

shell script to join 2 files on basis of 2 columns and if a match found then write some fields

abc.csv TBL_NAME,SANDBOX_NAME,SCRIPT_NAME ccti_prod_attdnl_ext,abs_ext,101_ext_table.m_diag.pset ccti_prod_attdnl_ext,abs_ids,101_ext_table.m_diag.pset xyz.csv ...
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30 views

“render” textfile with carriage returns (^M) and save output to file

I have a Python CLI program that runs for a long time and has a sort of progressbar, which basically prints some text in the loop without "\n" at the end, at the next iteration it prints "\r" to erase ...
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43 views

Check whether a process is running in privileged mode

I want to check if a specific process is running in privileged mode. If a process is running is privileged mode, necessarily the user running it is going to be root? I've noticed that when I use ...
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0answers
29 views

External monitor script has become unreliable

I have been using the following udev rule and bash script to automatically configure my external monitor for some time now, however recently the script has become unreliable, usually doing the ...
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0answers
8 views

Global [multiple sessions] directory stack

For the current zsh session I use dirs -v command to print the directory stack. I'd like to have an analogous tool that shows me the directory stack of all sessions, also the closed ones. Or if not a ...
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0answers
49 views

Write shrunken .img file to device file

I have a backup image of a device file /dev/sda3 that I created using: dd if=/dev/sda3 of=~/sda3.img. The image is very large, so I have re-sized it to remove empty space. My question is can I ...
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203 views

Recording shell output for interactive commands

While looking into a shell redirection problem, I found a couple of answers that pointed me to the script command. As I understand it, script just records in- and output of the terminal, and allows me ...
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62 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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312 views

$PATH variable on Fish Shell OS X

I have somehow screwed up my path variables with Fish shell on OS X. Is this the proper $PATH variable in the config.fish? user@host ~> more ~/.config/fish/config.fish set -g -x PATH ...
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100 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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0answers
235 views

Run git pull from a shell start-up script

I have Raspberry Pi that loads a shell script on start up. This script runs a python script, boot_camera.py, which is found in a repository. I Have a server which sends the Raspberry Pi a command ...
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31 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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141 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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0answers
83 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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111 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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134 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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129 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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38 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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0answers
133 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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982 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 ...