The shell is unix's command-line interface. You can type commands in a shell interactively, or write scripts to automate tasks.
1
vote
1answer
17 views
Wrapper script to list sourced/executed files
Is it possible to write a command which runs my.sh and prints every path sourced or executed by this script recursively - That is, without altering the original code at all? The idea is to verify ...
4
votes
3answers
70 views
CD into directory from HISTORY in a bash script or alias e.g. $(!!)
I often want to change into the directory of a file on my file system, but I'm not sure where the file is.
I search for it like so:
find -type f -name "myfile.txt"
Lets say for the sake of ...
6
votes
3answers
1k views
How to recover a shell after a disconnection
Am doing some work on a remote centos 5.6 machine and my network keeps dropping.
Is there a way i can recover my hung sessions after i reconnect?
EDIT: am doing some updating and installing with yum ...
1
vote
2answers
45 views
“or” in shell glob
I want to ls the files containing the substring "s1r", "s2r", "s3r" or "s19r" in their filenames.
I'm almost there!
Botched attempts:
ls *s[123][9?]r*
The above gives me only files including the ...
2
votes
1answer
41 views
Invoking a script with ld-linux.so?
I just downloaded a tar file that is supposed to include everything required to run a program that we can call some_binary. I extracted it's contents, and I see the following:
A binary (let's call ...
2
votes
2answers
56 views
Calling bash from sh (dash) with commands read from args, and “Unterminated quoted string”/“unexpected EOF”
Just thought I'd document this: I'm trying something very simple - set env variable in bash, and print it out:
$ bash -c "a=1; echo a$a;"
a
$ bash -c "a=1; echo a\$a;"
a1
Now I'd want this same ...
3
votes
2answers
60 views
How to print several files at the same time using lpr?
I am trying to print a number of files from shell using lpr. I enter something like:
lpr -P PRINTERNAME ./*/dir/file.pdf
but I get "lpr: No file in print request.".
When I use ls as
ls ...
1
vote
4answers
81 views
Problem understanding 'hash' command in a .sh file
So I wanted to install etherpad lite on a linux machine.
If I try to run it, I will get the Error "Please install node.js ( http://nodejs.org )"
the command 'which node' gives me the correct path to ...
2
votes
1answer
25 views
Installing packages and tools on a local non-standard directory
TLDR: What environment variables should I update to guarantee that my system has access to everything a package provides when building it on a non-traditional path?
I usually don't have root access ...
5
votes
2answers
191 views
Special character '#' in Perl SSH command
I try to send command using SSH in my perl script with # but it gets truncated right at #
Example:
Input text is :
$message = "Product ID # STK000134"
The SSH command is :
$execute=`ssh -q ...
8
votes
7answers
485 views
determine shell in script during runtime
As per my knowledge, to determine the current shell we use echo $0 in the shell. Rather I want my script to check in which shell it is running. So, I tried to print $0 in the script and it returns the ...
26
votes
8answers
2k views
Output “Hollywood-hacker-scene” from a shell
This might seem like a strange question, but what would you use for creating the typical hollywood hacking scene?
I got this request from a friend and my brain was blank. All I could think of was ...
5
votes
2answers
208 views
How do I add network or user source connection data to history entries?
I would like to modify the history settings for all users on the systems that I manage.
I would like it to contain the information from the connecting terminal like from who
sysadmin:/ # who
sysadmin ...
0
votes
1answer
108 views
Converting update-rc.d redis_6379 defaults to chkconfig command
I'm trying to run the commmand below to Centos and of course I get command not found. How do I then convert it to chkconfig ?
update-rc.d redis_6379 defaults
9
votes
1answer
226 views
How do you set up the environment for es?
I've been playing with es the last couple of days, and it (like rc) has the quirk/feature that it only runs its startup script (.esrc) on login. The usual way to run code in each interactive session ...
4
votes
1answer
275 views
How many users does Linux support being logged in at the same time via SSH?
I know Linux supports multiple users being logged in at the same time.
But what's the maximum number of users that can be logged into Linux at the same time?
I see there are there are 69 tty files ...
2
votes
1answer
95 views
Run remote shell daemon as non root user with tab-completion
I need to run any "remote shell daemon" (ssh, telnet, netcat, socat... I don't mind) as non-root user. The remote shell should provide tab-completion and I want to be able to browse history using ...
3
votes
4answers
80 views
Getting stdin from a named pipe
What I am trying to do is run python in a terminal window and redirect it's stdin from a named pipe. Then I write to the named pipe in another terminal and have that command execute on python.
...
6
votes
5answers
981 views
Why does shell Command Substitution gobble up a trailing newline char?
As per the following example, and as in my recent question In bash, where has the trailing newline char gone?, I want to know "why" it happens
x="$(echo -ne "a\nb\n")" ; echo -n "$x" | xxd -p
# ...
0
votes
1answer
49 views
How can I preserve new lines coming from a command's output during variable assignment?
Consider:
$ getfacl somefile.dat # The output is formatted and contains several new lines..
# file: somefile.dat
# owner: user1
# group: group1
user::rw-
group::r-- #effective:r--
...
3
votes
3answers
93 views
Count number of lines of output from previous program
I'm trying to count the number of lines of output a certain program produces. The problem is, the program takes a long time to run, and I want to display the output to the user. Is there a way to ...
4
votes
3answers
76 views
Why should 'Character Classes' be preferred over 'Character Ranges' In Shell (Bash)?
The Linux Command Line (Book - page count 47) says:
... you have to be very careful with them [character ranges] because they will not produce the expected results unless properly configured. For ...
0
votes
0answers
29 views
Pass process ownership to another shell [duplicate]
I didn't hear of anything like this, but It might be possible.
I often end up starting a process on a server and midway realizing that I would like to suspend that process and continue it inside a ...
0
votes
2answers
71 views
Supress expansion of * in echo
I am working on a script which dynamically executes some queries on daily basis. These queries are coming from a table in the database.
Here is the sample output of the query table:
...
1
vote
1answer
92 views
XML parsing using xmllint and customizing the output
I have xml file (say input.xml) of the following schema:
<?xml version="1.0"?>
<TagA>
<TagB>
<File Folder="FOLDER1M\1" File="R1.txt" />
</TagB>
...
0
votes
1answer
57 views
finger and who commands usage
I know that the finger command used to display information about local and remote users.
finger --> display users log in on local machine, even if remotely.
finger @hostname --> display users log in ...
0
votes
2answers
56 views
Cron job not running / not successful?
I have a couple of cron jobs set up to maintain a local copy of a remote database.
The first one downloads the latest version of the database from the remote machine, which runs every day and is ...
-4
votes
1answer
109 views
zsh: Is it worth the switch from bash? Is it the time? [closed]
I have been a bash user for years now. However, I find that zsh is increasingly gaining momentum. I came up with the following questions:
Is zsh really becoming that popular? Will it compete with ...
4
votes
8answers
1k views
Can shell variable include - character?
I am not able to use - in variables in shell. Is there a way to be able to use it, because I have one script which depends on such named variables:
$export a-b=c
-bash: export: `a-b=c': not a valid ...
0
votes
1answer
24 views
File inventories and logrotation
I want to collect a huge amount of data files on my actual netapp storage with the command file - f /path... > logfile.txt.
Through the huge data amount, the size of the logfile will be critical. ...
0
votes
0answers
57 views
Samba guest access
I have a home server with samba. with windows i can access and make folder(always with permission 777) like guest( no password ) without problem. But with linux, when i mkdir i can not modify this ...
13
votes
2answers
1k views
ls command: what does the first line mean?
I haven't been able to find this through internet, when I make ls -l I get this:
calico@A000505:~/Documentos$ ls -l
total 2020
-rwxr-xr-x 1 calico calico 8559 2010-11-16 11:12 a.out
-rwxrw-rw- 1 ...
3
votes
3answers
90 views
Can't process stdout with pipe as it comes
I'm running tshark on a fifo, and the following is a bare example of a loop that prints the output of tshark as it comes:
tshark -i $fifo | while read line; do
echo $line
done
The problem ...
3
votes
2answers
33 views
How to duplicate a stream and process both parts in a streaming way?
Sometimes I want to insert something in a pipeline for reporting or some other secondary use. It might be as simple as wc -l, or a more complex beast like awk or even a python script. It'd be nice to ...
1
vote
1answer
64 views
Safely convert unicode strings to printable characters
I have many HTML files containing mixed unicode strings like \303\243 and printable characters like %s. What I'd like to do is converting the unicode strings into printable characters in a safe way.
...
0
votes
2answers
39 views
Difference between eval and alias commands
what are the differences between eval and alias commands?
Examples:
x=‘ls -d -l $HOME’
$x
eval $x
alias y=‘ls -l -d $HOME’
y
11
votes
6answers
6k views
How do I can get the size of a file in a bash script?
How do I can get the size of a file in a bash script?
How do I assign this to a bash variable so I can use it later?
0
votes
2answers
70 views
read file record by record and do transformation to the subsequent record based on above record and write into another file
Data file is fixed length file, and I want to read the file record by record and do transformations to the subsequent records based on the prior records (and write the results into another file).
...
1
vote
1answer
40 views
Execute commands coming from a serial port
I have some hardware that is sending commands over /dev/ttyACM0 every once in a while and I'd like to execute them in a terminal. For example, if the ascii "ls" comes over /dev/ttyACM0, I'd like to ...
1
vote
8answers
96 views
remove content of directory in elegant way
I would like to remove all content of the current working directory.
How to do it in efficient and elegant way?
I have several files, directories and some of them starts with dot, like:
touch .abc; ...
1
vote
2answers
83 views
How to check in a shell script if an executable is running or not?
I have put an executable in a shell script file abc.sh. Now, I want to add one line in this abc.sh, to know whether it is running before my script starts or not and if yes, the kill that executable.
3
votes
2answers
286 views
How to skip file in sed if it contains regex?
I currently use the following simplified command to remove trailing whitespace and add a newline at end of file where needed:
find . -type f -exec sed -i -e 's/[ \t]\+\(\r\?\)$/\1/;$a\' {} \+
As ...
1
vote
3answers
316 views
Evalute passed in variable in bash
Is there a way to pass in a variable as an argument to a bash script and have it evaluated scoped by the bash script?
Given:
# cat /path/to/file/of/host/names
bob
tom
joe
etc...
# dofor
FILE=$1
...
0
votes
3answers
128 views
Is there any website having command line environment of Linux, for practicing commands? [duplicate]
I was wondering whether I could practice Linux commands and shell scripting, online, over a website which could provide me an editor to practice them. And I know that probably the easiest thing to do ...
0
votes
2answers
26 views
can't update with this error messg
I got this message:
not enough free disk space.... The upgrade needs a total of 31.8 M
free space on disk '/boot'. Please free at least an additional 31.8 M
of disk space on '/boot'. Empty ...
1
vote
1answer
121 views
How to create a password protected shell script [duplicate]
How can I create a password-protected shell script for read/write access. It should also be executable by all users without the password. I have sensitive information in the script.
27
votes
11answers
20k views
How can I get distribution name and version number in a simple shell script?
I'm working on a simple bash script that should be able to run on Ubuntu and CentOS distributions (support for Debian and Fedora/RHEL would be a plus) and I need to know the name and version of the ...
1
vote
3answers
118 views
Why is this Bash command using regex not replacing my brackets?
I have this command to go through all my files in my Music directory, and all subdirectories, and replace any square brackets in the file name with rounded brackets:
find /home/Music/ -depth -name "* ...
3
votes
2answers
154 views
Limit stdout from a continuously running process
I haven't had much luck finding an answer to my problem, but maybe I'm not asking for it correctly.
I have a process I startup like the following:
nohup ping 127.0.0.1 > log.txt >2>&1 &
...
1
vote
2answers
42 views
How to strip directory structure with command line (or script)
I have a large collection of files packed into a two-level directory structure with many, many, many folders.
In other words, I have a folder with a great many subfolders in it. There are no ...
