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, …).

learn more… | top users | synonyms (1)

10
votes
3answers
775 views

How does a shell execute a program?

If I compile a program using gcc, and try to execute it from the bash shell, what is the exact sequence of steps followed by bash to execute it ? I know fork(), execve(), loader, dynamic linker (and ...
0
votes
3answers
48 views

Where are shell variables stored?

For example, if I make a parameter expansion: $ b=1 $ echo $b 1 Where is b stored internally? I checked and it is not an environment variable because it is not listed by printenv. I'm writing my ...
1
vote
1answer
25 views

Shell Font Over SSH

I have a Linux machine (CentOS 7) in which I frequently SSH into from multiple devices. I have installed ZSH and Oh-my-zsh on the remote machine. I would like to install the following theme: ...
8
votes
3answers
25k views

Recovered deleted files on Mac by command line

I accidentally deleted a file by running: rm -rf ./Desktop/myScript.sh I think it's possible to recover the file, because the rm command removes temporarily. How can I recover the deleted file on ...
0
votes
1answer
45 views

Validate user response in shell script

My shell script is working fine and the files are copying to the remote directory. However I need to check if my INPUT_STRING is starting with S and also check if the files are present in the ...
1
vote
2answers
41 views

Help me please to find my misunderstanding about this little piece of shell script

Actually, I have a folder which contains several sub folders with lots of images in each. I am trying to gather all the names of the files in each sub folder in a text file (filesNames.txt) in that ...
7
votes
6answers
678 views

Number of files not containing given string

I read the question about how to find out the number of files that contain a certain string. This is possible with grep -l "string" * | wc -l. Is it possible to invert this, finding the number of ...
37
votes
5answers
2k views

Why is the wild card character * so different between commands zip and rm?

I put together a script to do some file operations for me. I am using the wild card operator * to apply functions to all files of a type, but there is one thing I don't get. I can unzip all files in a ...
4
votes
2answers
9k views

What is difference between pbrun and sudo command?

What is difference between pbrun and sudo command? I have seen people executing pbrun sudo su - what this means? I know su -, it will try to switch to root user. What speciality pbrun gives to sudo ...
10
votes
14answers
2k views

'ls -1' : how to list filenames without extension

ls -1 lists my elements like so: foo.png bar.png foobar.png ... I want it listed without the .png like so: foo bar foobar ... (the dir only contains .png files) Can somebody tell me how to use ...
0
votes
1answer
2k views

How to execute Netscaler commands through a remote machine via SSH connection

I have been trying to execute some NetScaler commands like "bind" & "unbind" through a Linux Box via an SSH Connection. Now the Problem is, Manually we are able to enter & execute commands on ...
0
votes
3answers
154 views

Where can I find the shell script for ls command? [on hold]

I am trying to understand how the ls command works, and I presume there is a shell script which defines ls somewhere in the filesystem. This correct? If so, where can I find it?
5
votes
2answers
93 views

How can I use the output of a command without using the mouse?

Imagine you issued a find command and now you want to use one line of the resulting output as an argument. $ find .. fileA fileB $ vi <CURSOR> # now do what to achive: $ vi fileB ...
14
votes
4answers
122k views

How do I exit or cancel a bad bash command?

I expect to get some flak for this, but I can't find the answer anywhere. It seems like it should be so obvious. Sometimes, when I type a bad command in a bash terminal, the cursor just jumps down to ...
0
votes
0answers
15 views

Unable to execute the rest of my shell script after installing Oh My Zsh [on hold]

I thought that here it will be better to ask for help with my problem. In a nutshell: I'm creating my custom shell script to simply customise my Mac. To make a short example: 1) I install OMZ using ...
3
votes
0answers
42 views

Exploit in bash script parameter possible?

I want to pass an e-mail address from a web form to a bash script. I'm using the following regex: /[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}/ Is this sufficient? Or could one embed an ...
1
vote
1answer
22 views

When a shell executes an external command/program - does that program have file descriptors?

There are alot of documents and discussion around the file descriptors of shells and how those file descriptors can be manipulated for redirection etc. My question is, when a shell command is an ...
1
vote
1answer
33 views

xkill Used On Desktop

Mouse accidentally clicked on Desktop while active with an xkill terminal command. Which makes it completely without use. Have used nemo command which resets everything as long as terminal remains ...
2
votes
4answers
50 views

Create text corresponding to multiple variable assignments from a single variable

I have a variable that has a value like this line=dog,/path1,/path2 What I want is to create a variable from the value; i.e dog should be the variable and want to get the below output: ...
2
votes
1answer
27 views

Find differences of ownerships between two home folders?

I have two home folders: /home/masi and /home/masi_backup and I would like to find the differences between files of the two directories. Pseudocode vimdiff <`ls -la /home/masi` <`ls -la ...
1
vote
1answer
40 views

Get the canonical path for a command

I'm writing a script that needs canonical path of certain commands. Since there could be symbolic links pointing to the actual commands, I use readlink -f to get the canonical path. But I'm not ...
19
votes
4answers
34k views

Pass shell variable as a /pattern/ to awk

Having the following in one of my shell functions: function _process () { awk -v l="$line" ' BEGIN {p=0} /'"$1"'/ {p=1} END{ if(p) print l >> "outfile.txt" } ' } , so when called as ...
2
votes
2answers
26 views

efficient wait until NAS boots to mount it

Problem: Server boots 3 minutes, Raspberry Pi boots 30 seconds. After a power outage, RPi boots faster and does not mount the NAS disk. This particular RPi needs disk to be able to record to it. ...
2
votes
2answers
5k views

Proper escaping of double quotations for curl post data?

I'm trying to test out a server, by sending it JSON data and reading the response. I need to POST data like {"item":"value with spaces"} but when I use curl I find that it sends the backslashes as ...
0
votes
3answers
51 views

Efficiently compare If variable exists and is not equal

I have a problem with the sh script syntax. I wrote a script for my Asus router. The script works perfectly. But I have this line: if [[ "$OldIP" && "$StartIP" != "$OldIP" ]]; then echo OK; ...
0
votes
1answer
24 views

how to echo/print block by block

I just started using tmux and butterfly and I need to scroll one panel. I tried Ctrl + b + ↑ but it scrolled the whole terminal instead of one panel. Is there any command line to display my ...
4
votes
2answers
6k views

Error with a file name containing parentheses

when I tried to change file name from old.file(1).gz to new.file.gz, It says syntax error, I am using ubuntu 12.04. mv old.file(1).gz new.file.gz bash: syntax error near unexpected token `('
4
votes
2answers
48k views

“not a valid identifier” when I do “export $PATH”

When I run export $PATH in bash, I get the error not a valid identifier. Why?
1
vote
4answers
53 views

How to gather the name of the files in each subdirectory into a text file in that subdirectory?

I wanted to save the names of all files in each sub directory into a text file in that sub directory, so I wrote this script: #!/bin/bash for X in "$PWD" * do if [ -d "$X" ]; then ...
2
votes
2answers
59 views

Split words from `read` and store to array?

How can I take input from read, split the words up by spaces, and then put those words into an array? What I want is: $ read sentence this is a sentence $ echo $sentence[1] this $ echo $sentence[2] ...
11
votes
3answers
1k views

Escape sequences in output of script called from ncurses application

I'm currently running mcabber as my Jabber client (which uses ncurses) in a tmux session on my homeserver. Locally i run iTerm2 as a terminal emulator, which supports the triggering of growl ...
0
votes
2answers
46 views

cut -c won't work on my .sh file [on hold]

I have tried the following commands cut -c-11 ifshell.sh cat ifshell.sh | cut -c-11 ifshell.sh cat ifshell.sh | awk '{print $1} | cut -c-11 ifshell.sh But every time I get the full contents of ...
0
votes
1answer
18 views

rc.local can't launch my program (raspbian linux)

I have a c++ program that is running perfectly fine if I run it by executing, sudo /Morreels/./launcher Sadly the same line (without sudo) won't work in the rc.local file on startup... When trying ...
0
votes
1answer
19 views

Why does the jobs command not work in shell script?

If I run jobs -l on command prompt it shows me the status of running jobs but if I run below file ./tmp.sh #! /bin/bash jobs -l It shows empty output. Why is that and how can I obtain information ...
-1
votes
1answer
15 views

can a service like isup.me be duplicated on the system for self? [closed]

The Internet or Web as I understand it runs on variety of servers. The browser is the client which gives a URI or URL which tries to go through varied ways to connect to the web-page and render the ...
13
votes
2answers
732 views

Colored output?

When I execute a command from a terminal that prints coloured output (such as ls or gcc), the coloured output is printed. From my understanding, the process is actually outputting ANSI escape codes, ...
20
votes
1answer
1k views

Why is nullglob not default?

In most shells nullglob isn't the default. That means, for example, if you run this command ls * in an empty directory, it will expand the *-glob to a literal ' * ', instead to an empty list of ...
20
votes
5answers
74k views

Using the not equal operator for string comparison

if [ "$PHONE_TYPE" != "NORTEL" ] || [ "$PHONE_TYPE" != "NEC" ] || [ "$PHONE_TYPE" != "CISCO" ] then echo "Phone type must be nortel,cisco or nec" exit fi The above code did not work for me, so I ...
16
votes
5answers
894 views

How to trick a command into thinking its output is going to a terminal

Given a command that changes its behaviour when its output is going to a terminal (e.g. produce coloured output), how can that output be redirected in a pipeline while preserving the changed ...
0
votes
1answer
56 views

How to pull database file from physically connected android device

I am trying to copy WeChat database file called EnMicroMsg.db so I can view it in SQLite browser. With my Nexus 7 tablet rooted and physically connected, the usb debugging checked I ran the following ...
5
votes
2answers
12k views

Cant ssh, connection terminates immediately with exit status 254

The most recent thing I remember is changing the soft and hard memlock ulimit to unlimited. Now I cant ssh into the machine. This is the ssh log. Authenticated to IP ([IP]:22). debug1: channel 0: ...
-1
votes
1answer
25 views

NodeJS - error npm undefined symbol uv_fs_realpath

i'm trying to install yo (linux) using npm npm install -g yo but i get this error : node: symbol lookup error: node: undefined symbol: uv_fs_realpath when i only type npm, it return same error ...
-1
votes
0answers
12 views

MongoDB Shell Commands

i want Run shell command(s) from MongoDB , i connect to My MongoDB With MongoVUE now i want execute shell Command like ls -l can i do it From MongoVUE ?
1
vote
1answer
20 views

tmux: how to bind a key to launch shell command?

I use tmux to develop, with two panes: one to edit the code, and one to compile it. I need to switch pane very often to launch the compile command (say "mvn install"). How can I bind a key (say ...
1
vote
1answer
44 views

Extracting files to current directory

I want to find and tar/archive all my scripts ending .sh so I wrote something like that: touch ~/archive.tar; find ~ -type f -name '*.sh' -exec rvf ~/archive.tar {} \; The problem is that after I ...
18
votes
3answers
3k views

Difference between 'ls' and 'echo $(ls)'

Consider the two shell samples $ ls myDoc.html SomeDirectory someDoc.txt and $ echo $(ls) myDoc.html SomeDirectory someDoc.txt The first executes ls which, as I understand, appends the contents ...
3
votes
1answer
96 views

Syntax error with variable containing quotes

I have a bunch of Linux machines behind 2 gateways. To connect to set one I do ssh -o ProxyCommand="ssh gateway1 nc %h %p" machines_behind_1 ssh -o ProxyCommand="ssh gateway2 nc --proxy %h %p ...
0
votes
1answer
31 views

Is using env and export the same thing?

I'm wondering whether this (From https://www.digitalocean.com/community/tutorials/how-to-read-and-set-environmental-and-shell-variables-on-a-linux-vps): env VAR1="blahblah" command_to_run ...
0
votes
1answer
27 views

how to color specific strings in standard output and standard error [duplicate]

How do you color specific strings in standard output and standard error? For example: gpg --verify Outputs either a good signature or a bad signature string. How can I color the good one, green; ...
0
votes
1answer
56 views

How does this equation gives numbers random between two values?

How does this equation gives random numbers between max and min divisible by divisibleBy echo $(((RANDOM%(max-min+divisibleBy))/divisibleBy*divisibleBy+min))