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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8
votes
1answer
634 views

stderr over ssh -t

This sends output to STDERR, but does not propagate Ctrl+C (i.e. Ctrl+C will kill ssh but not the remote sleep): $ ssh localhost 'sleep 100;echo foo ">&2"' This propagates Ctrl+C (i.e. ...
5
votes
4answers
721 views

Check if a folder has a certain type of file present

How could I check if a file has a file of extension .java? So far I have: for javaFile in *.java ; do { echo "The file $javaFile has : " >> ~/Desktop/externalServers.txt ...
0
votes
1answer
214 views

How do you keep the password hidden when invoked during the su command?

This is the first time it has happened to me where I am using the su command and it actually displays the password on the terminal and doesn't stay hidden. Here is my code snippet: sshpass -p ...
0
votes
1answer
293 views

script to compare two string “foo” and “bar”

I'm going to create a script that should print "foo" or "bar" when a user's input is "foo" then print "bar" or when the user's input is "bar" then print "foo", otherwise show "invalid string". Here's ...
85
votes
6answers
92k views

How to split the terminal into more than one “view”?

From vi, if you issue the command :sp, the screen splits into two "views", allowing you to edit more than one file from the same terminal. Along those same lines, is there a way to have multiple ...
3
votes
2answers
247 views

How do I echo an expression with both single and double quotes?

I have tried many things, but I'm new to the shell. Is it possible to have both double and single quotes within an echo? I want to generate echo "scan 'LPV',{FILTER => "(PrefixFilter ...
5
votes
2answers
211 views

How exactly does `if $cmd ; then $cmd ; fi` differ from `$cmd && $cmd`?

In an answer to another very good question I made the following assertion: According to my reading of the POSIX specs, the use of one or the other makes no difference from a parsing standpoint. ...
3
votes
2answers
166 views

how to parse a file that is changed continuously using awk?

for example if we have a file contains : Hello world Hello earth Hi everybody we can easily parse it to get the first and second columns of the lines contains the word Hello using awk: awk ...
0
votes
2answers
48 views

How to create a variable $ldir at your home directory that contains the relative path to letters?

If there's a directory on your Desktop called letters: 1) How to create a variable $ldir at your home directory that contains the relative path to letters? 2) How to copy a text file f1.txt to the ...
0
votes
0answers
34 views

convert many eps files in a single pdf or ps file using shell scriptI

I have SSt12.OLR.1.eps, SSt12.OLR.2.eps SSt12.OLR.3.eps SSt12.OLR.4.eps ......and covert these eps files into single pdf or post script file. please suggest a shell script.
0
votes
0answers
16 views
5
votes
2answers
295 views

How to send an alert if the DHCP range exceeds using shell script?

I've install and configure DHCP server on CentOS 6.5. I've also added a subnet to the dhcpd.conf file as follows: subnet 192.168.1.0 netmask 255.255.255.0 { option domain-name-servers 192.168.1.2, ...
2
votes
0answers
314 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 ...
1
vote
4answers
154 views

How to set the process won't be terminated when the terminal stops

[Edit] Make it simple. I invoked java xxx... on Machine A using putty to connect from Machine B. However I cannot reach Machine B. How can I connect Machine A from Machine C to set the running ...
1
vote
4answers
290 views

List all commands that a shell knows

What can I type at my shell (which happens to be bash) that will list all the commands that are recognized? Also, does this differ by shell? Or do all shells just have a "directory" of commands they ...
4
votes
3answers
4k views

Case-insensitive substring search in a shell script [closed]

I'm trying to create a script which runs a command and compares the output of that command to a certain string to see if it contains that substring, ignoring the case of the string needed to be ...
4
votes
4answers
3k views

What is the most efficient way to move a large number of files that reside in a single directory?

CentOS 5.x I apologize if this is a repeat question. I've seen a lot of similar questions (regarding deleting files) but not exactly the same scenario. I have a directory containing hundreds of ...
5
votes
2answers
2k views

Is there a unix command line tool that can analyze font files?

Given a directory of font files (TTF and OTF) I'd like to inspect each font and determine what style (regular, italic, bold, bold-italic) it is. Is there a command line tool for unix flavored ...
5
votes
2answers
159 views

What does ${3#?} do?

I have a script with the following variable assignment: TEST_VARIABLE=${3#?} What does the ${3#?} do?
1
vote
2answers
234 views

Run jar on startup in all *nix based systems

I have a jar file which I need to run at startup in all distros of Linux. My previous question here, gave me an idea a rough idea on X-servers. Since I wasn't able to perform startup, I moved on to ...
10
votes
4answers
7k views

What's the easiest way to find an unused local port?

What's the easiest way to find an unused local port? Currently I'm using something similar to this: port=$RANDOM quit=0 while [ "$quit" -ne 1 ]; do netstat -a | grep $port >> /dev/null if ...
3
votes
2answers
203 views

Rescue value from second last line

After I run a script, I've got the following lines: PyMOL(TM) Molecular Graphics System, Version 1.4.1. Copyright (c) Schrodinger, LLC. All Rights Reserved. Created by Warren L. DeLano, ...
1
vote
2answers
121 views

Temporarily freeze a process upon shell interaction

Let's say on a single console I have tail -F running, showing the output of many log files in realtime. Sometimes I need to run commands there too, however, and examine their output briefly, without ...
2
votes
3answers
195 views

grep on a Java Method

Lets say I have a java class called DirectAction some of the methods in the class have the word "action" or "Action" What is the grep command to get the names of all the methods who have "Action" or ...
5
votes
2answers
500 views

Why doesn't my loop over the output of ls work?

I am trying to feed Directory names into a for loop. My code is as follows: td='/Test/TopDir/' cd "$td" for x in $(ls -d */ | cut -f1 -d'/'); do echo x=$x done The top directory I run this on ...
3
votes
1answer
198 views

How to find all paths not compatible with Windows?

On most Linux filesystems, NUL (\0) is the only invalid character in paths (and / is reserved as the path separator). Windows has a complicated set of rules for valid paths. Rather than fixing paths ...
0
votes
1answer
162 views

bash completion on posix mode [duplicate]

I would like to use an interactive posix bash shell but the autocompletion feature doesn't work. When i type the tab character it simply prints a tab. The tab completion only works when i'm on a non ...
1
vote
1answer
80 views

bash completion on posix mode

I would like to use an interactive posix bash shell but the autocompletion feature doesn't work. When i type the tab character it simply prints a tab. The tab completion only works when i'm on a non ...
1
vote
2answers
251 views

Difference between command `ls 2 >tmp >tmp` and command `ls > tmp`

I am relatively new to Linux systems. I don't understand what is the difference b/w ls 2>tmp >tmp and ls > tmp. They both seem to do essentially the same thing, creating a file tmp and ...
1
vote
2answers
378 views

How to show specific lines from specific columns of a file

First off, I'm not allowed awk, sed or perl. For my assignment I was given a file of employee list: Marketing Ranjit Singh FULLEagles Dean Johnson Marketing Ken Whillans FULLEagles ...
0
votes
1answer
76 views

Linux script for printing name [closed]

I have to Prompt the user to enter his/her name and Print all combinations of three letters from the name. How to write script for this?
2
votes
1answer
214 views

How to create an executable bash script for these commands?

I wish to create an executable bash script that will run the following commands as root, that is, using sudo su iptables-save | awk '/^[*]/ { print $1 } /^:[A-Z]+ [^-]/ { print ...
1
vote
1answer
108 views

Prevent active file removal on an NFS filesystem

I clear my logs using following script - find "." -mtime 1 -type f -print0 | xargs -0 rm -rf But it deletes the active files also and creates .nfs… files instead. Is there any way to prevent ...
10
votes
2answers
2k views

Closing a file descriptor, >&- vs <&-

In the bash tutorial I am reading, it says that if you open a file descriptor for reading, i.e. exec 3< echolist Then you must close it like this, exec 3<&- However, if you open a file ...
3
votes
2answers
766 views

Start zsh with a custom zshrc

I want to be able to start zsh with a custom rc file similar to the command: bash --rc-file /path/to/file If this is not possible, then is it possible to start zsh, run source /path/to/file, then ...
1
vote
1answer
84 views

GeeXbox ls shows no date?

Recently, I tried connecting to my GeeXbox via WinSCP but got an error indicating the output of ls could not be parsed. Apparently, my ls does not include a time stamp! What might be the cause and ...
4
votes
2answers
10k views

lftp: login, put file in remote dir and exit in a single command: proper quoting help

I want to use lftp -c to do an entire session in one go (as I'll be launching this from a script later on) and I managed with -e but that ofc leaves me with the interactive session which I don't want. ...
0
votes
1answer
39 views

better use of find - rvm.sh

I am trying to find rvm.sh as I am receiving the infamous rvm is not a function error. The file in most linuxes is supposed to be at /etc/profile.d/rvm.sh However on opensuse it is not there so I ...
3
votes
5answers
1k views

Listing directories based on size from largest to smallest on single line

I can use the following command to get a list of directories and their sizes and sort them from largest to smallest (in the example I renamed the directories to numbers to make this easier to ...
1
vote
1answer
59 views

Using cat to modify ~/.bash_profile seems to remove __git_ps1 compeltely

I want my prompt to display the current git-branch when inside of a repo directory. e.g., [desktop repo(master)]$ In my terminal I can type: cat <<EOF >> ~/.bash_profile ...
0
votes
0answers
49 views

how to pass asterisk as a parameter to getopts [duplicate]

I wrote a shell scripts with getopts to take arguments. But I want to pass an asterisk as an argument, for example script -a"Hello * all" -b"Another argument" if I echo the -a argument from the ...
2
votes
1answer
98 views

Capture symbolic link into Unix/Linux variables

Say I have a folder with a series of symbolic links: ussdv103:en195d; default$ pwd /oradba/app/oracle/admin/database1 ussdv103:en195d; default$ ls -ltr exp -> ...
0
votes
3answers
682 views

SSH Agent-Forwarding works, but what about sudo -u username no shell/ permissions? composer

Working on a remote server (A) I want to use my local SSH-Keys to access a repository on another server (B) that is not controlled by me. Generally this works like a charm. I log in as myUsername ...
1
vote
1answer
56 views

Use a bash function in a pipelined command

I have a command similar to: ... | sort -u -V. Since some versions of sort do not support the -V flag, I thought it would be great if I made a function that conditionally adds the flag. But, it seems ...
4
votes
1answer
251 views

Blank lines when executing “grep | xargs” in a “find -exec”

I'm trying to list all directories of a web server that are blocked by Apache via a .htaccess (containing deny from all). I've managed to get the list of blocking .htaccess but when I try to extract ...
23
votes
1answer
30k views

How do you extract a single folder from a large tar.gz archive?

I am using this command on a 5GB archive tar -zxvf archive.tar.gz /folder/in/archive is this the correct way to do this? It seems to be taking forever with no command line output...
1
vote
1answer
1k views

Press a html button via shell script?

i am currently trying to write a script to change some parameters on a webpage via a shell script. I can change the values in the textboxes without any problems, but i can't seem to figure out how i ...
1
vote
4answers
741 views

renaming multiple files increment order

I have the following files SSt12.precip.374.sub.climatology.ctl SSt12.precip.2874.sub.climatology.ctl SSt12.precip.3764.sub.climatology.ctl SSt12.precip.6774.sub.climatology.ctl I want to rename ...
0
votes
1answer
60 views

egrep part required for svn hook script

I am trying to write a pre commit hook script to Enforcing tag naming convention like < application>_ < project >_ < version>_ < iteration> this using a shell script can anyone ...
1
vote
2answers
284 views

run shell scripts in a sequencing way?

I have 4 shell scripts and I want to run them in a sequencing way: script1 -> script2 -> script3 ->script4 in a local machine can I ensure this by make the scripts executable and creating a new ...