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)

1
vote
2answers
461 views

How to move files from one directory to a nested directory using SSH?

I'm new to SSH. I would like to know how to move all the files, not the folder or directory, to an existing folder or directory two levels down.
9
votes
1answer
32k views

How to create bootable flash for “efi-shell”

Current Intel server chipsets include a built-in "efi-shell" which appears to basically be a simplified 'NIX with a command set suitable for manipulating some nifty UEFI boot options. It is also the ...
3
votes
2answers
867 views

Can the shell warn me if a program is waiting for standard input?

Let's say I want to search for a string in a big file: grep foo bar.txt | less, but I actually type grep foobar.txt | less. Now, grep is waiting for me to type something on the terminal. It appears ...
1
vote
2answers
111 views

Reduce redundant logfile

I often have longer redundant log files, redundant in the sense that blocks of text repeat with minor changes. The length of the files makes it difficult to spot the actual information. I had the idea ...
2
votes
2answers
3k views

How to remove element from the list?

I have written a command that output a list of hostnames, e.g. : clab148node11 clab148node12 clab148node15 clab148node16 Now, I would like to remove those nodes that do not respond to ping. For ...
1
vote
1answer
4k views

What does sourcing a file mean in a shell? [duplicate]

Possible Duplicate: Different ways to execute a shell script What happens when I issue the following command: source devenv.csh How does it differ from running it just as devenv.csh ?
0
votes
2answers
33k views

Redirecting the content of a file to the command “echo”

I have a file named my_file.txt whose content is just the string Hello. How could I redirect its content to the command echo? I know I have the commands less, cat, more... but I need to do it with ...
4
votes
2answers
7k views

What is the difference between ping -w and ping -W?

What is the -w (deadline) flag in ping for? I cannot find a description of it in the ping man page; only for -W, which takes seconds as a parameter. What is the difference between them, and how can I ...
3
votes
4answers
24k views

How to send many commands to shell and wait for the command behind ends

Hello I have around 20 commands and I have to send all of this to Unix shell, and copy the result, but I don't know how to do it. I am not sure about what shell I have, because it is a small program ...
7
votes
2answers
16k views

Good method to compare time?

I need to check for the current time and abort the script if it is not proper time of day I am supposed to run it. Also, if anyone else runs it, it should abort. For example: I need my script to only ...
0
votes
2answers
1k views

Comparison of shells? [closed]

Do shells have any actual advantages or disadvantages? They can all run any binary, they all support pipes and > (output to file). Why would one choose bash over sh, or sh over ksh, etc? Why does ...
1
vote
1answer
122 views

How get program name that produced an IO error redirected to a LOG in a nohup command?

I have a program that executes other programs in the background. The main program would be programA, and the programs executed by the main one, would be program1a, program1b and program1c. I need the ...
2
votes
3answers
2k views

Linux Shell Script - Send command over TCP to Sharp Aquos

I'm writing a shell script that needs to send an 8 character string terminated with a x0d to a Sharp Aquos TV. An example is 'POWR1 \x0d' (POWR1 followed by three spaces and LF) The documentation ...
1
vote
1answer
2k views

Outputting last modification date to another file?

I'm trying to read the number of lines in a file, and the last modification date of that file (e.g. if it was last modified Jan 18, 2013, it should output 2013-01-18), then append the data to the ...
3
votes
1answer
251 views

Passing all files of specific filetype in current and subdirectories

I have constructed an elaborate 500+ character command with many arguments and switches to autosign multiple PDF documents. I'm using JSignPDF and I'd like to use it's batch mode including the ...
3
votes
3answers
4k views

How to execute a bash script on multiple directories?

I have a conv.sh script that loops over MP3 files in the current directory and converts them into OGG. I have also several directories {F1, F2,..., F20} at /path/to/Files/. How should I execute ...
1
vote
3answers
1k views

Finding lists of files with specific permissions

I looked into the find command and came up with find . -maxdepth 1 -perm 521 > test.txt to output the permissions to a text file, but is it possible to do it just using, for example, simple ...
8
votes
2answers
337 views

Difference between [[ $variable ]] and [[ -n $variable ]]?

In bash, are [[ $variable ]] and [[ -n $variable ]] completely equivalent? It appears to be the case judging by the output below, but I see both forms of usage prevalent in shell scripts. $ z="abra" ...
4
votes
4answers
1k views

What are commands to find shell keywords, built in functions and user defined functions?

I was discussing with my friend on how the commands are parsed in the shell, and he told me that bash searches the command in following order List of aliases List of shell keywords List of ...
3
votes
1answer
904 views

Why does sendmail work differently in different shells?

The following code works when I directly run it in bash shell: SUBJECT="SUBJECT-"`date`; MAIL_FROM="abc@site.com"; MAIL_TO="abc@site.com"; MAIL_CC="abc@site.com"; MAIL_FILE="/path/of/html/body.html"; ...
8
votes
5answers
2k views

mkdir -p for files

mkdir -p will create a directory; it will also make parent directories as needed. Does a similar command exist for files, that will create a file and parent directories as needed?
3
votes
5answers
592 views

Copy Sequential Files

I have 12 files named dmp_000, dmp_001, etc, all the way to dmp_011. I would like to copy all of them to rdmp_000, rdmp_001, and so on, sequentially so the numbered files coincide. There must be an ...
3
votes
4answers
5k views

How to pipe the stdout to a file if the current command is already being piped through gzip

So I have this command I need to run then disown: innobackupex-1.5.1 --user=root --password=**** --stream=tar ./ | gzip - > /data/myfile.tar.gz How do I pipe any output to a file? adding ...
7
votes
3answers
618 views

OpenSSH - map aliases in ~/.ssh/config to IP addresses in command line

Is it possible to query ~/.ssh/config in the command line? Let's say I would like to retrieve what IP address does the particular alias point to in a separate program, is it possible?
18
votes
6answers
19k views

How can I switch between different audio output hardware using the shell?

I use my laptop with an external monitor which has speakers. When the monitor is attached through HDMI I can switch (using the GUI: Sound Setting --> Hardware) between the normal laptop audio output ...
5
votes
2answers
4k views

bourne shell if [ -e $directory/file.$suffix ]

I've been looking inclusive I even checked the if manual for bash and tried in cli mode. #!/bin/sh CONFIG_DIR="/var/opt/SUNWldm/" read option if [ $option -eq 9 ]; then ret=1 elif [ -e ...
1
vote
2answers
3k views

Parsing string by awk and get only elements without pipes or semi colons

I would like get this string line AUGUSTYN|Stanisław|3589238 without | and : I tried something like that: cat baza|grep "AUGUSTYN" -n|awk -F '|' '{print $1,$2,$3,$4}'` (baza is my file with ...
1
vote
1answer
403 views

how to setarch for each bash session

I am using bash as my default shell. I don't have root access. But I would like to customize my bash by setarch. So the question is how to do this automatically? Currently, I have to manually run ...
3
votes
1answer
316 views

No output from inotifywait | awk

I'm attempting to use part of a one-liner found here: Script to monitor folder for new files? When I try the following procedure I get no output whatsoever and I cannot figure out why. In terminal ...
1
vote
1answer
143 views

Unsure about the behaviour of my script when writing to log file

I have a very simple ksh script and at certain points I want to write to a log file. I use the following commands in two places... print "Directory listing 1:\n" > ${LogFile} ll >> ...
4
votes
1answer
4k views

What are special prompt symbols for busybox's sh support?

I want to setup a time prompt on PS1. But, there is no document about what are symbols the busybox support. Is there any one know? Here are all which I knew. PS1='\u@\h: \w \$'
5
votes
2answers
2k views

Setting a shell variable in a null coalescing fashion

I'm really fond of "null coalescing", where you can set a variable to the first "non-null" value in a list of things. Many languages support this, for example: C#: String myStr = string1 ?? string2 ...
3
votes
2answers
752 views

$BASHPID And $$ differ in some cases

I'm reading "BASH pocket guide of Oreilly". It said: The process ID of the current Bash process. In some cases, this can differ from $$. Above explanation , explained $BASHPID variable. ...
4
votes
3answers
3k views

Find functions, commands, and builtins [duplicate]

Possible Duplicate: Executing user defined function in a find -exec call Suppose I have the following bash code: !#/bin/bash function print_echo (){ echo "This is print_echo Function" ...
1
vote
1answer
11k views

Convert any Date format in unix

How can I convert any user inputted date into yyyy/mm/dd? For example user can input date in one of the following formats 20120121 , 2012-01-21, 01/21/2012, 01/21/2012 etc. But I need to convert any ...
3
votes
2answers
4k views

Attach to existing screen session, but new window

So I have a screen session running on one terminal/machine I would like to write a script that would attach to that screen session on another machine, but to a new window in that screen. Does anyone ...
2
votes
1answer
656 views

Exit status ($?) of 148 upon Ctrl+Z

I just customized my .bashrc to include the exit status of the last command, so I get fancy prompts like ☑ larsmans@host:~$ and I no longer have to re-run commands to see their exit status because ...
9
votes
1answer
787 views

What is the significance of the dot in bash commands and how is it different from an asterisk?

I'm trying to understand the significance of the dot in bash and how it differs from an asterisk. Can someone please elaborate? For example, what's the difference between cp -ar /foo/. /foo2/ and cp ...
5
votes
3answers
155 views

Can any shell do argument-level interactive search?

Sometimes I need to reuse certain long arguments like paths. If I use history search (CTRL+R), I may find some command that contains the path, but I still need to delete anything else in the old ...
5
votes
2answers
5k views

Executing a shell script from remote server on local machine

Imagine a shell script on the remote server as #!/bin/bash rm /test.x How can I (if possible) to execute this script from my local machine to delete /test.x file on my local machine. Obviously, the ...
2
votes
3answers
22k views

Copy file from Windows shared folder to Unix

I am totally new to Unix. I am writting a script which will copy files from a Windows shared folder to Unix. In Windows, when I type \\Servername.com\testfolder in Run command I am able to see ...
0
votes
3answers
285 views

How to delete number of lines from file repetitively

I've read How do I delete the first n lines of an ascii file using shell commands?, it is helpful. However I've a file something as below (please consider 2 columns as 2 different files): 1 4 1 4 1 4 ...
1
vote
1answer
128 views

What is the “~/” directory?

I'm trying to locate where some files are stored and I can easily browse to them via ssh by going to "cd ~/foldername", however, I have no idea what directory "~/" actually is. When I browse around ...
3
votes
2answers
2k views

Changing tmux .bash_profile behavior

I have a script in my .bash_profile that prompts for X sessions to boot. When I launch tmux, I get this prompt that I had only intended for the TTY login. Is there something I can put in ...
0
votes
3answers
900 views

Proper place to put shell prompt(PS1) when use sh/bash/zsh together

I'm using dash(sh) or bash or zsh. If possible, I would prefer to put in common place. I want to put proper PS1 settings when I interactive with shell, so these situation should be considered login ...
5
votes
1answer
315 views

Can I add to my groups in the current (shell) process? [duplicate]

If I add myself to a group, it applies only to newly launched processes. Actually it's more restricted than that; it seems to apply only to new logins. I'm not sure what the exact mechanism is, but ...
2
votes
1answer
354 views

Can I transfer running process from dead ssh [duplicate]

Possible Duplicate: How can I disown a running process and associate it to a new screen shell? I have started (as expected) a long copy process from ssh shell (putty) which died due to ...
2
votes
2answers
131 views

How to supress the display of previous job details?

When I run a process in the background the process ID gets displayed in the command prompt. For example: $ gvim 1 & [3] 9584 Now when I run another process the state of the previous one also ...
2
votes
2answers
146 views

What does this syntax mean “${i%.avi}.mp4” [duplicate]

Possible Duplicate: How do ${0##*/} and ${0%/*} work? I have encountered this type of syntax somewhere on the web : for i in *.avi do ffmpeg -i "$i" "${i%.avi}.mp4" done how does ...
2
votes
3answers
1k views

What's the difference between these ways of accessing the shell?

From what I know it seems that there are many ways to access the shell on Linux. So far the methods I know are: To use a program such as Terminal or Konsole To use the shortcuts CTRL + ALT + F1-6 To ...