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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5
votes
1answer
104 views

Shell one-liner for adding a line in the middle of a pipe

I write a script which sends the input file to CPP, then to grep, then to a certain program: cpp $1 | grep -v "#" | theprogram But, "theprogram" requires the input to start with a certain constant ...
21
votes
5answers
11k views

echo a file without the first and last lines

Is there a simple way I can echo a file, skipping the first and last lines? I was looking at piping from head into tail, but for those it seems like I would have to know the total lines from the ...
2
votes
2answers
494 views

Want a seperate file to store mysql username, password, and database name

I have as script that dumps a mysql database, and compresses the file. What I want to do is have another (edit) file which can change the username, password and database name. Then somehow connecting ...
0
votes
2answers
64 views

Convert a float to the next integer up as opposed to the nearest?

The context is there are 2 variables that get divided to a floating point result like so: printf "%0.5f\n" $(echo 305/15 | bc -l) 20.33333 How can I always round up to the next integer i.e. 21? ...
2
votes
3answers
78 views

Remove files from listing that are created/modified on Saturday

I am not sure if it is possible. I do ls -l, it gives all the files in the current directory. Is there a way to say list only files that weren't created/modified on Saturday's with shell command?
2
votes
1answer
80 views

Problems with find, xargs and egrep

I this is what I what I'm trying to end up with (except working) find ./ -mindepth 1 -type f -mtime +60 -print0 | xargs -0 egrep -vZ 'vvv|iii' What am I doing wrong? $ ll total 0 -rw-rw-r-- 1 ...
0
votes
1answer
685 views

Command not found when run with sudo bash

I ssh into my machine and then, in order to run some commands, I need to sudo bash first. In an interactive terminal session, if I do this: [vagrant@33 ~]$ sudo bash [root@33 vagrant]# which bundle ...
-2
votes
1answer
109 views

How do I automate this in a shell script?

I'm using the application PlexConnect on my home server (a headless OSX box) and I have to ssh in (from an iMac) and manually kill the Python process sometimes with the following: ssh 192.168.0.7 ...
2
votes
3answers
14k 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
2answers
39 views

Number of occurences of letters in a word?

I would like to find out the number of occurrences of each of the alphabets in a word. Eg input aabbbddd output a@2 b@3 c@0 d@3 How can I perform this using shell script?
0
votes
2answers
378 views

How to list files and directories of a mount point

Given a mountpoint such as /dev/sda1 how can I list the contents of this file system using shell script. My objective is to delete the oldest file in this drive.
4
votes
3answers
425 views

Change case of n-th letter in a string

I want to change the case of the n-th letter of a string in BASH (or any other *nix tools, e.g. sed, awk, tr, etc). I know that you can change the case a whole string using: ${str,,} # to lowercase ...
4
votes
2answers
264 views

Can multiple mv commands be run in the same directory (race condition)?

I'm moving a large number of files (400K+) from one directory to another and I have the following script to do so (too many files for the mv command to work directly): for file in *; do mv $file ...
2
votes
2answers
1k views

Left and right square brackets treated differently by sed/bash

I have a file with the following contents: [root@server list]# cat filenames.txt [AAA','ACMEDEMO2','ACMEDEMO3','ACMEDEMO4','RENTCOGH','TESTENT','DORASINE','LOKAWINK','BBB] [root@qa4app01 list]# I ...
3
votes
2answers
549 views

What is the format for piping a message into sendmail?

I am using the following command to create messages on the fly, and send them: echo "Subject:Hello \n\n I would like to buy a hamburger\n" | sendmail email@example.com It seems that when you send ...
1
vote
1answer
35 views

Using double or no quotes with wildcards

I came across this article which attempts to explain the find command.It gives an example of find /tmp -iname "data*.txt" now this article here states that Double quotes do not suppress the ...
3
votes
2answers
375 views

Execute code on remote machine and copy the results back

I'm using some old Fortran code that uses some peculiar memory handling. To make the long story short, it runs on my local machine but fails on the remote one. This is why I would like to ssh to my ...
1
vote
3answers
985 views

What return/exit values can I use in bash functions/scripts?

I want to know what return values we can use that will not be mistaken by for ex. SIGINT? ex.: $sleep 10 $#hit ctrl+c $echo $? 130 so I know I must not use anything like return 130 or exit 130 so ...
6
votes
3answers
527 views

How do I print '-e' with echo?

I know that echo -e is not an ordinary command. I have tried echo '-e' and echo \-e but they still don`t work.
1
vote
3answers
755 views

Different “history” command output after reconnecting via SSH

Why do I get different results for the "history" command for the same user after I reconnect a disconnected SSH session? I connect to a server using putty (SSH), say as root My network gets ...
1
vote
3answers
75 views

How to remove matching files from directory A in directory B in the command line?

I have some duplicate files in directories A and B, how could I delete the dupes in B using the filenames from A in bash? How to do it in other shell's is a welcome bonus.
1
vote
1answer
191 views

RYSNC over SSH not working for restricted shell

I need to give access to some Mr X in my production server so that he can push files to my server. Since there is no necessity to give him shell access , I decided to use restricted shell (rssh) so ...
1
vote
1answer
369 views

How do I get a list of the values of matching attributes using xmllint and xpath?

I'm trying to use xmllint to parse names of Solr cores from the configuration file. This works: xmllint --xpath /solr/cores/core/@name solr.xml |grep -Po '(?<=name=")[a-z-]+(?=")' And it returns ...
2
votes
1answer
88 views

Help with using quotes in grep searches

I have a file with variables in it of the form a(i)%b(j)%c where the a, b, and c are always the same, but the indices i and j may be different (including multiple characters). So I've played around ...
2
votes
1answer
455 views

GDB cannot exec my test program

My computer run with Ubuntu 14.04. GDB seems to be abnormal in different account. For example I make a very simple test. I write a file under ~/test/test.c like this: #include <stdio.h> ...
0
votes
2answers
219 views

Bash getting integer expression expected

I have following script to check disk usage #!/bin/bash # set alert level 90% is default ALERT=10 OIFS=$IFS IFS=',' storage=$(df -H | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{ print $5 " " ...
2
votes
2answers
223 views

Adding “ubuntu” user to Vagrant ubuntu instance

I am using a vagrant box : uname -a Linux precise64 3.2.0-23-generic #36-Ubuntu SMP Tue Apr 10 20:39:51 UTC 2012 x86_64 x86_64 It does not have ubuntu user setup , instead it has vagrant one ,so I ...
0
votes
4answers
46 views

Print only directories with more than 31 files

I am using this script to count files on my directory and sub-directories: for i in $(find . -type d) ; do printf "$i %s\t" ; ( find $i -type f | wc -l ) ; done This script works fine. What I ...
4
votes
1answer
158 views

Executing a “fork bomb” safely

We've all seen the "fork bomb" that will render a host non-responsive, even if executed in an unprivileged shell: Warning: Do not execute the following shell script. Just don't. :(){ :|:& };: ...
2
votes
2answers
74 views

Tar a list of files which don't all exist

I'm running a command from a script like tar -c -f ar.tar a b c d where b, c, and d may not exist, and may be directories. The solutions that I've come up with are piping the output of ls -d to ...
3
votes
4answers
252 views

what is the difference between `find .` and /home/user/* as an input to for command

What is the difference between find . and /home/user/* as an input to for command.? For example: for var in $(find .) do echo "$var" done or for var in /home/user/* do echo "$var" done In the ...
1
vote
1answer
45 views

How portable is this shell assignment?

VAR=${VAR:-value} The purpose is to set the environment variable VAR to value unless it's already set. I see it works in bash and dash, but how portable is it?
2
votes
2answers
92 views

Typing text from a shell script [duplicate]

I'm new to shell scripting. I'd like to know if there's a command similar to "echo" for displaying text in a terminal, but instead of simply displaying it immediately, it actually types it, like if ...
2
votes
1answer
71 views

Append same timestamp to multiple filenames

I have several files that I ftp each hour. The receiving system needs to have some sort of identifier that they came from the same batch, so I would like to append a timestamp to the filename. That ...
0
votes
0answers
279 views

python error using an executable with Z shell

I'm getting this error from the Unix Z shell (I'm on Mac): python: posix_spawn: /System/Library/Frameworks/Python.framework/Versions/2.6/Resources/Python.app/Contents/MacOS/Python: No such file or ...
5
votes
3answers
574 views

How to view last 5 lines from last created/modified file?

Every day I have to take backup and update the status to support teams at particular time for which I need to check last 5 lines of last created/modified *.aff file in a directory and update them. ...
0
votes
1answer
21 views

Loop across url with static tokens with Oauth

I need to write a loop where I need to pass a "token" (which is fixed) and a variable (i) in the url. Is there any way I can achieve that? I wrote the following code but it is not working. If I put ...
2
votes
2answers
97 views

for loop to iterate through some file nth position

How do I iterate for nth file in a for loop in unix? below some code I have tried but not succeeded #!/bin/bash # n=2 array=( "CTL_MLPOSDTLP1_1.ctl" "CTL_MLPOSDTLP1_2.ctl" "CTL_MLPOSDTLP1_3.ctl" ) ...
2
votes
3answers
203 views

how to run the dialog command with proccess

Please look on my code – ( bash script ) I want to display both dialogs on the screen on the same time, one dialog display the: tail –f from - /var/log/proccess1.log , and the second dialog ...
1
vote
4answers
562 views

How to subtract two times in shell

I nee to subtract two lines which is in the format of time in shell. Th time format is hh:mm:ss I used the code below to get the time. cat /var/log/kern.log |grep usb |tail -2| awk '{print $3}' The ...
0
votes
2answers
73 views

How can I redirect the same message to both stdoud and stderr (without temporary object)

It is easy to redirect stdout or stderr to the same output (file or one of the 2 std output) with a 1>&1,>&2 and/or >file. Is there a way to send the same output to both the std ...
0
votes
1answer
39 views

Check for subdirectory

A)I used the following code to get the modified date of a file. But this is also selecting the subdirectories and thus returning an error. How van I fix this. for file in $1/*; do echo `stat ...
4
votes
2answers
1k views

How to show only total file size of particular extension by `du` command

I have a hundreds of pdf files and html files in a directory. And I want to know total size of pdf files. By command du -ch /var/foo I can see total file size but I only need last line, the total ...
32
votes
5answers
9k views

Does /usr/sbin/nologin as a login shell serve a security purpose?

In my /etc/passwd file, I can see that the www-data user used by Apache, as well as all sorts of system users, have either /usr/sbin/nologin or /bin/false as their login shell. For example, here is a ...
0
votes
1answer
39 views

elif command is throwing error [closed]

Hi is the below elif command correct? elif [[ "${FILECOMMAND}" = "" ] && [[ -f ${ZIPFILE} ]||[ -f ${ZIPFILE3} ]]] I am getting an error when I run it.
0
votes
1answer
31 views

Pre-process 1 single option

I've got a Shell script (intended for Linux/Mac/Cygwin users) that wraps an executable JAR. Before passing the arguments (long or short form) to the Java program, I need to pre-process one single ...
2
votes
1answer
139 views

Writing to an interactive prompt

I’m using the ftp command line tool and want combine scripted input with user input. With only user input the prompt looks like this: ftp> But when I try to insert some input with a script, like ...
1
vote
2answers
48 views

Shell, howto extract letters from $line1=“Test this… test this!”, and print one by one

I am writing a script, which I would like to spice up a bit. What I need, is a loop, which takes one letter at a time, including space, and then write it on the screen, like an old typewriter would ...
2
votes
1answer
87 views

PS1 prompt showing different on local and remote console

This is my PS1 prompt: export PS1="\[\e]0;\u@\h: \w\a\]${debian_chroot:+($debian_chroot)}\[\033[01;35m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ " That shows perfect in remote (SSH) ...
3
votes
2answers
411 views

Syntax error: word unexpected on io redirection on file descriptor ≥10

I have the following shell script on debian 7: #!/bin/sh case "$IFACE" in lo) # The loopback interface does not count. # only run when some other interface comes up exit ...