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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0
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1answer
32 views

I ran `zsh -v` and now I have no shell history [closed]

I just installed zsh today to try it out. I was trying to check my zsh version and I accidentally entered zsh -v which is the verbose option. Now I can't seem to use reverse search on history. How ...
4
votes
1answer
77 views

Problem combining -or and -exec with find command

I'm finding that when I use find's -or operator in combination with -exec, I don't get the result I expect. When searching for .cpp and .h files, the command works as expected if I don't use -exec: ...
3
votes
2answers
123 views

leaking memory with shell script and tty [closed]

I'm running a shell script on a raspberry pi to communicate with a arduino. Every hour my ram gets used up by about 50 megabytes more. The script itself just connects to ttyACM0 (the arduino's usb ...
7
votes
2answers
186 views

Why is a variable visible in a subshell?

The Learning Bash Book mentions that a subshell will inherit only environment variables and file descriptors, etc., and that it will not inherit variables that are not exported: $ var=15 $ (echo ...
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votes
6answers
168 views

How to change to normal user in the command line when logged in as the root user?

I log into an system through root via ssh. How do I become the normal user or another user on the system?
5
votes
4answers
219 views

Is there a difference between read, head -1, and sed 1q?

The following commands seem to be roughly equivalent: read varname varname=$(head -1) varname=$(sed 1q) One difference is that read is a shell builtin while head and sed aren't. Besides that, is ...
3
votes
3answers
208 views

Method for storing/remembering one liner commands

Often when configuring and adjusting unix-based systems I use a lot of one-line commands that are difficult to remember. For example, to determine what version of ntp (the time server) is running, you ...
4
votes
2answers
88 views

How to capture ordered STDOUT/STDERR and add timestamp/prefixes?

I have explored almost all available similar questions, to no avail. Let me describe the problem in detail: I run some unattended scripts and these can produce standard output and standard error ...
4
votes
3answers
318 views

Is there any CLI/terminal slideshow app?

I'm asking myself: is there, on linux, any software that can build and show simple slides on terminal, like the slides you make on Libreoffice Impress (but way more simple)? This would be a great ...
14
votes
4answers
1k views

Do we have more history for cd?

cd - can move to the last visited directory. Can we visit more history other than the last one?
2
votes
2answers
43 views

Interacting with a running interactive console program from a different process

I have a console program with an interactive shell, similar to say, the Python interactive shell. Is there an easy way to start this interactive program A and then use another program B to run A? I ...
21
votes
4answers
2k 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 ...
1
vote
1answer
167 views

/bin/sh: error importing function definition for `some-function'

I encountered this error when updating bash for the CVE-2014-6271 security issue: # yum update bash Running transaction (shutdown inhibited) Updating : bash-4.2.47-4.fc20.x86_64 /bin/sh: error ...
0
votes
1answer
75 views

Copying files with multiple extensions

I would like to copy files with multiple extensions to a single destination directory. For example, I can use the following command to copy all .txt files in the working directory to a directory ...
-1
votes
2answers
4k views

How to delete a file in Arch console?

pacman stopped working and asked me to delete a file if "another package manager isn't working". What is the file for deleting files?
2
votes
4answers
75 views

Bash - How do I loop through subdirectories and extract the files

I have a directory called 10K_TIF (main directory). Within this main directory are multiple sub-directories each containing tif images. I want to read each TIF image and extract its path using a bash ...
1
vote
1answer
38 views

Interactive Shell Session from Java

I want to run a series of commands from Java. I came across few forums that explain how to execute multiple commands using getRuntime().exec(command) and defining command as String[]. But I want to ...
0
votes
4answers
53 views

How to get process id of a command

We are running some command in batch mode. We need to do some more tasks once the existing command is done, so we need to wait until this command is done. For example: bsub -q gui -I calibre -drc ...
0
votes
2answers
28 views

Rsync'ing system, exclude doesn't seem to work

I'm trying to make a full filesystem backup of a server through rsync, following this guide. I'm using the following command: rsync -aAXH --progress --delete --stats --exclude={\ "/dev/*",\ ...
5
votes
4answers
457 views

How to cd automatically after git clone?

I want to automatically cd to the directory created by the clone command after I git cloned something. Shell: ZSH if that matters.
0
votes
1answer
33 views

How to move cron commands into a script?

Can someone give me an example that shows how to put Cron commands into a script? Using these commands as an example: find /home/network/public_1 -type f -ctime -1 -exec ls -ls {} \; find ...
1
vote
1answer
53 views

Is it possible to create a Linux environment without a traditional command shell?

i.e. Using something like IPython, re.pl, or somesuch as a login shell, instead of bash/ksh/etc. Using initscripts, etc. written in Python or some other scripting language, and making no use of ...
3
votes
1answer
44 views

Make program in a pipe to think it has tty

Test environment: $ mkdir testdir $ cd testdir $ echo | tee "file name" Now, ls will print file?name (under Ubuntu GNU bash, at least), while ls | cat will print file and name in separate lines. ...
2
votes
2answers
532 views

Assign Subshell background process pid to variable

I am currently starting a background process within a subshell and was wondering how can I assign its pid number to a variable outside the subshell scope? I have tried many different ways but MYPID ...
6
votes
2answers
981 views

How to trigger error using Trap command

I am using Ubuntu 12.04.2. I am trying to use "trap" command to capture abnormal or error in my shell script but I am also trying to manually trigger "Error" exit. I have tried exit 1, but it won't ...
1
vote
1answer
23 views

Icon stops loading after the application restarts

I have a application which uses "self-restart" mechanism. It kills itself and runs again. When I run it first time (with .desktop file) it loads its icon correctly. The problem is that when it ...
79
votes
3answers
5k views

Why not use “which”? What to use then?

When looking for the path to an executable or checking what would happen would you enter a command name in a Unix shell, there's a plethora of different utilities (which, type, command, whence, where, ...
1
vote
3answers
109 views

How to find md5sum of files on remote machines by doing ssh?

I am running my below shell script on machineC which gets the md5sum of my files in my PRIMARY directory in machineC itself. #!/bin/bash export PRIMARY=/data01/primary for entry in "$PRIMARY"/* do ...
1
vote
1answer
41 views

du skip symbolic links

I cannot find an example of what I want to do and, from what I'm reading, the default behavior of du on my system is not the proper default behavior. If I ls my /data folder, I see (removing the ...
2
votes
2answers
46 views

List of subdirectories that contains a particular file name

I am wondering if i can do this in a single shell command. I am in home directory and want to find a list of subdirectories that contains a particular file. The file name and the depth is always ...
1
vote
3answers
72 views

How to get the pid of a process and invoke kill -9 on it in the shell script? [duplicate]

I have an application server which we start by running this below command and as soon as we run the below commnad, it will start my application server /opt/data/bin/test_start_stop.sh start And to ...
2
votes
1answer
50 views

Bash - how to make explicit operator precedence without creating a subshell

I'm sure this is posted somewhere, but I haven't been able to find it. In Bash, how does one specify operator precedence (aka command grouping) without creating a subshell? In most other languages ...
-2
votes
0answers
19 views

UNIX .vimrc settings not preserved after running Screen command

After the terminal window first appears, I run Screen to split the screen horizontally. I notice however that my settings for VIM in .vimrc are not "preserved". Is there a way to fix this? I am ...
1
vote
1answer
77 views

Why are UNIX shells like this and how can I work around it?

One of the things I've noticed about BASH and other UNIX shells is that, by default and when used in typical ways, they spawn subshells for almost everything. e.g. foo=$(grep "someword" ...
0
votes
3answers
43 views

Shell pattern matching vs. regular expressions occurence [duplicate]

I am relatively new to Unix, and I stumbled across one curiosity. Some shell constructs like case or find, employ pattern matching, but it is not quite regex. Other commands, like ed, sed, vi, and ...
-20
votes
3answers
207 views

Which amongst the given option is TRUE about login shell?

Which amongst the given option is TRUE about the login shell? The login shell varies every time the user logs in. The kernel decides on the availability of the shell during login. The login shell ...
0
votes
1answer
42 views

Changing my default directory in passwd changes my prompt

I don't understand what's happening in this scenario. I changed the home directory of a user by editing the /etc/passwd file instead of using usermod -d. It worked: the default directory wasn't ...
6
votes
4answers
3k views

Convert linux sysuptime to well format date

I want to display /proc/uptime in well format as: DD:HH:MM:SS /proc/uptime give me up time of system in seconds, is there a standard solution that convert seconds to this format?
0
votes
1answer
50 views

How do I switch from bash to zsh? [duplicate]

I can start zsh with zsh. How can I make it be the default for new terminal windows? Will it be ok to copy my .bashrc to .zshrc to get things like my customized PS1 prompt.
0
votes
1answer
40 views

Permission denied while getting the md5sum of a file using shell script?

I am running my below shell script which gets the md5sum of a files in my PRIMARY directory #!/bin/bash export PRIMARY=/data01/primary for entry in "$PRIMARY"/* do local_md5sum=/usr/bin/md5sum ...
0
votes
2answers
32 views

How can I sudo su and change directory just after?

I would like to create an alias that does something like this: alias userYYY='sudo su userYYY; cd /a/path/that/only/userYYY/has/access' So then from my command line, I am logged in with a sudoer ...
1
vote
1answer
19 views

Increase character width in Ubuntu server shell?

Is there any way to increase the character width from 80 to something higher in the shell in an Ubuntu server?
3
votes
1answer
30 views

More shell scripts than one in one text file?

I am learning shell scripting for my introductory UNIX course at my university, and I`m curious if is it possible to have more than one shell script in one text file. What I mean by that is, for ...
0
votes
1answer
48 views

How to invoke shell function in string? (bash)

I want to invoke shell function in string. Here is my use case: function envfoo() { env ENV_FOO=foo $@ } function envbar() { env ENV_BAR=bar $@ } $ envfoo env |egrep ENV_ ENV_FOO=foo $ ...
0
votes
2answers
36 views

Add space after 8 characters then add space after every 4 characters

Here is the sample input: AbbigailAbieAbbyAbbi Using sed, I have separated them into 4 characters but seems like I got a problem because I have to separate the first 8 characters first then add ...
8
votes
4answers
473 views

How do I remove spaces from shell variables?

I have done the following at command line: $ text="name with space" $ echo $text name with space I am trying to use tr -d ' ' to remove the spaces and have a result of: namewithspace I've tried ...
1
vote
2answers
157 views

I accidentally GZIPed a whole bunch of files, one by one, instead of using tar(1). How can I undo this mess?

I'm new to the gzip command, so I googled some commands to run so I can gzip an entire directory recursively. Now while it did that, it converted each of my files to the gzip format and added .gz to ...
5
votes
3answers
140 views

Bash script error with strings with paths that have spaces and wildcards

I am having trouble getting the basics of Bash scripting down. Here's what I have so far: #!/bin/bash FILES="/home/john/my directory/*.txt" for f in "${FILES}" do echo "${f}" done All I want to ...
5
votes
3answers
134 views

I am trying to find a better/easier way to count alphabetic characters in a file or shell variable

I have a file containing the following text: we are going to write something 1 2 3 wc tells me I have 1 line 9 words and 38 characters. I'm looking to count the 26 letters only (a-z, no numbers or ...
2
votes
2answers
788 views

Using sudoers to allow php to run command

I am trying to get my php page to run this command: shell_exec("sudo /home/xbian/433Utils/RPi_utils/codesend {$num}"); So I added this entry to my sudoers file with visudo: www-data ALL=NOPASSWD: ...