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)

5
votes
1answer
110 views

Bash Script — ffmpeg not being invoked as expected

I'm working on a bash script to convert my music library to ogg* but executing the right command is somehow eluding me. This is the line that should accomplish it: ffmpeg -i "${file}" -f flac pipe:1 ...
4
votes
3answers
352 views

Exiting a shell script with nested loops

I have a shell script with nested loops and just found out that "exit" doesn't really exit the script, but only the current loop. Is there another way to completely exit the script on a certain error ...
21
votes
1answer
535 views

What does it mean to have a minus sign as the first character of a command in htop output?

In htop, or other commands that show process status, all bash processes have in the command column /bin/bash but one process has in the command column -bash What does it mean?
-2
votes
1answer
48 views

Execute bash snippets directly in shell? [closed]

Is there any way to execute small bash snippets in the shell? If you don't want to edit a file again and again and test it by executing it again and again (in fact by jumping forth and back between ...
0
votes
2answers
32 views

How to find file that has read permissions from root directory?

I am trying to find files with read permissions from root directory and save them under /home/student/abc direcory: find / -type f -perm a+r -exec cp /home/student/abc {} + but it shows me the ...
2
votes
1answer
37 views

Start sh in a specified directory from inittab

I am currently working on an embedded Linux system. For it to be similar to our other products I need to have it start a shell in a specified directory on boot, accessible using the serial port. For ...
5
votes
0answers
95 views

Peculiar Solaris integer comparison behaviour

This one caught me unawares! We have a Solaris machine (version: SunOS 5.8) hosting a pivotal script/process which has been running for many years without complaint. We recently had cause to have a ...
2
votes
1answer
19 views

Running make for LFS complains about [ and about missing gawk

I'm having a strange error when I'm trying to start the make process for LFS using the LiveCD SVN Trunk. When I go to run make it gives me; $ make /bin/sh: 1: [: -ne: unexpected operator -e Missing ...
6
votes
4answers
848 views

Add a newline into a filename with `mv`

It's a serious question. I test some awk scripts and I need files with a newline in their names. Is it possible to add a newline into a filename with mv? I now, I can do this with touch: touch ...
2
votes
1answer
76 views

Convert IP Address to Coordinates using database

I have a file which contains IP and I wanted to compare it to Coordinates using a local database (instead of API). I tried following a process and break down to pieces and created scripts referring ...
1
vote
1answer
60 views

Extracting trace information using gawk

I am new to awk programming and am using gawk to extract trace information from a mrt file in order to use it further for analysis. I have successfully been able to extract trace information from a ...
6
votes
3answers
306 views

Should I use a slash at the end of path variables in shell script or not? [closed]

Today when writing my shell script. A question suddenly comes to my mind. Since cd /target_dir and cd /target_dir/ both works. Should I add a slash at the end of my path variables in a shell script? ...
13
votes
1answer
201 views

Update bash history on others terminals on exit of one

I know this question has a similar interpretation, as its asked here keep updating (and duplicated here). But what I'm trying to achieve is a bit different. I don't like the idea of my prompt ...
3
votes
3answers
167 views

awk and newlines in the input data

I want to find files in a directory and identify by their mimetype, not by the extension of the files. I'am using this command to determine the mime type: % find . -type f -print0 | xargs -0 -I{} ...
1
vote
1answer
63 views

Batch move all files from subdirectories to parent directory, but files have same name

I have many files in sub-directories that I would like to have all moved to the parent directory. Ex: 20150530XXXX/1.jpg 20150530XXXX/2.jpg 20150530XXXX/3.jpg 20150530XXXX/4.jpg 20150531XXXX/1.jpg ...
54
votes
2answers
2k views

Security implications of forgetting to quote a variable in bash/POSIX shells

If you've been following unix.stackexchange.com for a while, you should hopefully know by now that leaving a variable unquoted in list context (as in echo $var) in Bourne/POSIX shells (zsh being the ...
0
votes
1answer
65 views

route -n gives output “route: fscanf”

If I boot my system and no interface has an IP address I get the above output. However if I give an interface an IP, even if I remove it again, this will disappear. Why does this happen? Is it that ...
2
votes
2answers
154 views

bash completion in Posix mode

I would like to use an interactive Posix bash shell but the autocomplete feature doesn't work. When I type the Tab character it simply prints a tab. The tab completion works only when I'm in a ...
17
votes
4answers
15k views

Solving “mv: Argument list too long”?

I have a folder with more than a million files that needs sorting, but I cant really do anything because mv outputs this message all the time -bash: /bin/mv: Argument list too long I'm using this ...
0
votes
2answers
59 views

How do you search ! in man sed?

You cannot search ! directly because it puts process behind. For instance, you cannot search ! in sed man. How can you search ! in man?
0
votes
1answer
47 views

Issue a command in each directory

I have 3 directories: dir1 contains two subdirs. In every subdir there is a slackbuild. I want to build all slackbuilds, staying in the parent directory. I have tried (cd *;sh *ld) But it only ...
88
votes
7answers
8k views

Why is cd not a program?

I've always wondered why cd isn't a program, but never managed to find the answer. Anyone know why this is the case?
4
votes
1answer
8k views

Linux - Sending a command to a screen through a shell script? [duplicate]

I'm trying to figure out how to make a script that will be able to send commands to a screen that will execute within whatever the screen is doing. Is this possible, and if so, how is it done? I've ...
3
votes
1answer
139 views

Autocomplete issue in bash with equal sign (=)

I am trying to make autocomplete work and wroted a piece of code to demonstrate an issue I faced up: $ cat completion.sh function _completion_command() { compopt +o bashdefault +o default +o ...
2
votes
2answers
66 views

ssh command with quotes

I have an odd error that I have been unable to find anything on this. I wanted to change the user comment with the following command. $ sudo usermod -c "New Comment" user This will work while ...
0
votes
1answer
48 views

Practical usage of “shift” shell builtin command?

I checked the /usr/bin/ssh-copy-id(part of openssh-client package at least under Debian) shell-script and it contains following if-statement: if [ "-i" = "$1" ]; then shift # check if we have 2 ...
5
votes
6answers
589 views

How do I check if a variable exists in bash?

I need to check a variable's existence in an if statement. Something to the effect of: if [ -v $somevar ] then echo "Variable somevar exists!" else echo "Variable somevar does not exist!" ...
1
vote
1answer
50 views

Move files from multiple directories to another system

Let's suppose I have a folders in the source system: AB1, AB2, AB3. And I have the same folder names AB1, AB2, AB3 in the destination system. I want to move AB1 files to AB1 and AB2 files AB2 and ...
4
votes
2answers
47 views

How can I disable bash traces?

For any command that I execute in the terminal a comment like + command appears. For example for ls it shows + ls --color=auto.
4
votes
4answers
1k views

How can I make shell aliases available when shelling out from Vim?

In my .zshrc, I declare some aliases. Eg, which dbstart shows the contents of that alias. If I open vim from that shell, it is a child process. In Vim, I can run shell commands with :! some_command. ...
1
vote
2answers
59 views

How do i search for certain sections of a file and then extract only relevant information within that section?

So I have a text file that is a server report and has about 1000 lines of information in it. I'm trying to write a script that can search the report for only certain pieces of information I'm looking ...
14
votes
3answers
2k views

What are the shell's control and redirection operators?

I often see tutorials online that connect various commands with different symbols. For example: command1 | command2 command1 & command2 command1 || command2 command1 && command2 ...
18
votes
3answers
599 views

Use of ^ as a shell metacharacter

I wrote a small script today which contained grep -q ^local0 /etc/syslog.conf During review, a coworker suggested that ^local0 be quoted because ^ means "pipe" in the Bourne shell. Surprised by ...
-3
votes
2answers
45 views

Transform text records using only a “for” loop

I have an input file that is text, consisting of lines that look like: 352|C|PAID|7036|VOICE|01-FEB-12 I need to split each line into fields at the | (vertical bar) characters and output each field ...
0
votes
1answer
54 views

Counting program fails in arithmetic test

having a little trouble with this rather basic script. This script works on Bash in my macbook pro, but not on my Linux Mint desktop, which also uses bash. I can't figure out what's wrong with it, ...
2
votes
3answers
81 views

Execute a shell command upon a click event in a web page

Is there a way to execute a bash command when I click on a text in a browser? The web page is on computer A, the browser is on computer B : I want to execute the code on computer B, e.g hsetroot to ...
8
votes
4answers
59k views

How do I exit or cancel a bad bash command?

I expect to get some flak for this, but I can't find the answer anywhere. It seems like it should be so obvious. Sometimes, when I type a bad command in a bash terminal, the cursor just jumps down to ...
1
vote
2answers
52 views

Unable to store ascii value in a variable

I am trying to convert hex to decimal to ascii and store it in a variable. I am using the following code. HEX=30 DEC=`printf "%d\n" 0x${HEX}` echo "$DEC" ASC=`printf \\$(printf '%03o' $DEC)` echo ...
3
votes
5answers
129 views

How to add column in the beginning of file using perl?

I want a Perl one-liner that checks whether the first fields of an input file is the file's name and, if it isn't, adds the file name as the first column on every line. Example written in shell : ...
0
votes
2answers
33 views

Does kali distro not use /etc/environments file?

I appended a path to /etc/environments file and now it is like so: mindaugas@Kali:~$ cat /etc/environment | tr ":" "\n" PATH="/usr/local/sbin /usr/local/bin /usr/sbin /usr/bin /sbin /bin /sbin" I ...
-6
votes
1answer
46 views

Copying and relative Home

Your current directory is oxford. Make a copy of the file named outline.doc and place it into the sample_dir directory, using relative pathnames. I've attempted everything. sample_dir1 `-- ...
0
votes
1answer
41 views

Combine curl and base64 into one command?

I'd like to POST the Base64 encoding of a file to a server, combining curl and base64 into one command that I can execute. I've tried the following: curl 'http://localhost:5000/files' -X POST -H ...
16
votes
2answers
11k views

What is the difference between interactive shells, login shells, non-login shell and their use cases? [duplicate]

Possible Duplicate: Difference between Login Shell and Non-Login Shell? I have been looking at /etc/profile. bash.bashrc to see how they are run, and notice that some are executed by ...
68
votes
9answers
23k views

How do I delete a file whose name begins with “-” (hyphen a.k.a. dash or minus)?

How do you remove a file whose filename begins with a dash (hyphen or minus) -? I'm ssh'd into a remote OSX server and I have this file in my directory: tohru:~ $ ls -l total 8 -rw-r--r-- 1 me ...
0
votes
2answers
71 views

Bash script that detects if a file is the correct size

I'm trying to make this bash script dispatch and email when it detects that a certain type of file (files ending in ".gz"), which was last modified 24 hours ago, is below a certain size in a ...
6
votes
2answers
95 views

Why does the terminal echo keystrokes when commands are running?

I was recently running tail -f on a log file of a server that was running, trying to diagnose a bug, when I accidentally bumped the keyboard and typed some characters. They got mixed in with the ...
0
votes
2answers
31 views

Which file should be sourced in .devishrc to permanently change the hitch-file? [closed]

By default, in DEVISH (at least for me) the hitch file used is mhitch.py... I can change the hitch using the -h option for the shfile command, but I need to permanently set it to something... Any ...
1
vote
3answers
82 views

How do I get the current line count from xargs?

I want to grab every 5 images in a directory and merge them together into a new file with a unique filename per 5 image group. find *.jpg | xargs -n 5 -i convert {} -append {#}.png This is really ...
0
votes
1answer
34 views

What is the behaviour of & operator [duplicate]

I am trying to chain the commands in linux, I am using ubuntu 14.04 distribution. The aim to create a directory and go into that directory. Generally we do this mkdir foldername cd foldername ...
6
votes
2answers
1k views

BASH base conversion from decimal to hex

In Bash, how does one do base conversion from decimal to another base, especially hex. It seems easy to go the other way: $ echo $((16#55)) 85 With a web-search, I found a script that does the ...