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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0
votes
6answers
284 views

sed to replace with backspace

I have trail.txt, which contains spice netlist. Now I want to replace all expanded parameters to one line only i.e. remove + and append that line to previous line. trail.txt data + net06706 ...
0
votes
1answer
26 views

remove _ as prefix from the multiple files in a directory in Soalris [duplicate]

I have to remove _ which is as prefix for a file. I used: for i in _*.txt; do mv ${i} ${i/#_/''}; done but it does not change the names of the files which has space in between as _abc xyz-abc.txt ...
1
vote
1answer
26 views

Installed PDFInfo with Homebrew Cask but no command associated with “pdfinfo”

First, please excuse this very basic question. I'm sorry I have to ask it, but it's very difficult to find your way around the shell at the beginning. I installed pdfinfo with Homebrew Cask: brew ...
2
votes
2answers
46 views

Seems like some basics are missing from ubuntu…or I haven't set them up?

I can't define a shell variable like so: $a = "hello" echo $a echo a $a a all lead to nothing. Also, this command doesn't work for me: $ echo "HELLO HOW ARE YOU?" | tr '[:upper:]' '[:lower:]' ...
2
votes
3answers
204 views

How to pass argument with char ( in remote path?

I'm trying to move a file with rsync to a remote location, The file has be be named : DRRS_(H264).mp4 but when I try : rsync -azR output.mp4 user@server.com:encoded/somepath/DRRS_(H264).mp4 it ...
2
votes
2answers
137 views

How to generate a random string in a profile alias?

I have an alias in my server's /etc/profile which generates a random directory on command, like this: alias rdir="mkdir -p ./`cat /dev/random | tr -cd 'a-z0-9' | head -c 8`/" But it turns out this ...
0
votes
2answers
72 views

Shell Script: Sending input to background process

I am using the following script to watch a folder, and if the size changes and a file doesn't exist, it runs a script. #!/usr/bin/sh SCRIPT="dim_import/xdir" while true; do size=$(du -s ...
0
votes
0answers
18 views

display JPEG Exif header with od (Octal Dump)

there are several command line tools to show Exif header of JPEG images. I wish to see the same info with od (octal dump) $ jhead 1430472877538-0.jpg File name : 1430472877538-0.jpg File size ...
1
vote
2answers
100 views

CasperJS and PHP In Cron Job Cannot Open Files, Works Fine When Run Manualy

I recently got a new DigitalOcean LEMP environment with Ubuntu. I tried making an SH script that uses CasperJS to scrape data from an external website to a JSON file, and a PHP script to parse the ...
0
votes
1answer
61 views

How to execute shell commands in a loop from within a bash script?

I am new to bash and need help badly. I want to write a script which will run on my android phone & perform the following things: echo "1" > /sys/kernel/mm/ksm/run wait for 2 minutes: then ...
4
votes
1answer
2k views

“>/dev/null 2>&1” in `if` statement

I don't understand the below if condition. I know that /dev/null 2 > &1 is sending output to error stream (please correct me if I am wrong). But I don't get it when it is in an if condition ...
0
votes
3answers
640 views

The best way to add Unix Shell variables to CURL GET request

Let’s say I use curl –X GET command with the following link: “$WEBSITE_URL/ACTION_NAME/ACTION1;id=$ID?Command=TEST&id1=$ID1&id2=$ID2&id3=$ID3” As you can see, there are some $variables ...
0
votes
1answer
40 views

Writing an install script for CentOS

Every time I deploy a VPS server, I install VNC server. But every time I have to do this: yum groupinstall Desktop yum install tigervnc-server yum install vnc yum install firefox (etc.) Can I ...
2
votes
2answers
71 views

How can I setup a separate bash environment with only GNU utilities on OS X?

For the last 5 years, I have used linux as my everyday OS for performing scientific computing. My work recently gave me a Mac that I will be the primary user for the next few months. I keep running ...
5
votes
3answers
208 views

How to forward between processes with named pipes?

The /tmp/in, /tmp/out and /tmp/err are named pipes, already created and opened by some process (for reading, writing and writing, respectively). I would like to create a new process that pipes its ...
52
votes
6answers
21k views

How to check if a shell is login/interactive/batch

I think I understand the differences between an interactive, a login and a batch shell. See the following links for more help: What is the difference between a 'Login' and an 'Interactive' bash ...
0
votes
0answers
24 views

Why rsyslog leaves the last file in spool directory

Suppose I am using a rsyslog remote server (R1) & have a client box (C1). C1 is configured to sync up and use R1 for logging (over port 514; TCP) The spool directory is '/var/log/rsyslog'. Now, ...
76
votes
17answers
72k 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 ...
2
votes
1answer
97 views

Finding out what sh is [duplicate]

I am writing a set of scripts that I want to be portable, but I need to know whether sh on the current platform stands for bash, ksh, or ash. Is there a clear way to do it? What comes to my mind ...
3
votes
4answers
763 views

Print a string including single quotes and other special characters

How can I write this with an AIX script correctly? My requirement is to write this command in test.txt: clock=$(prtconf -s | awk '{print $4,$5}') I tried this command: print 'clock=$(prtconf -s | ...
1
vote
2answers
24 views

How can I properly escape a string to be passed to a shell with a command argument [duplicate]

How can I properly escape arbitrary commands? For example: sudo -u chris sh -c 'echo "\"leftright\""' The above echos: "leftright" How would I echo out: "left'right" I've tried the ...
0
votes
1answer
679 views

openSuse, not running the cron job

I have created a cron job in the /etc/cron.d/dispatchingEmail_I the permissions of dispatchingEmail_I are the following: -rw-r--r-- 1 root root 84 Sep 11 19:52 dispatchingEmail_I content of ...
0
votes
0answers
17 views

What does a hash key preceded by an exclamation key (!#)mean? [migrated]

See the following script from scala tutorial, What does the !# mean? #!/bin/sh exec scala "$0" "$@" !# object HelloWorld extends App { println("Hello, world!") } HelloWorld.main(args)
6
votes
4answers
723 views

sed ranges aren't always able to match only one line

Consider the following range: 1,/pattern/. If pattern matches on the first line, the range matches for the whole file: $ cat 1.sh #!/usr/bin/env bash set -eu seq 1 4 | sed -rn '1,/'"$1"'/p' $ ./1.sh ...
3
votes
4answers
172 views

Comparing each file in two directories and copying it to one if it differs from it's counterpart

How can I compare all files in two directories and copy the ones that are different to one of the directory. For example, say we have dir1 and dir2: dir1: build.gradle gradle.properties ...
5
votes
7answers
599 views

Turn list into single line with delimiter

I have to take a list (loads) of IP addresses in this format: 134.27.128.0 111.245.48.0 109.21.244.0 and turn them into this format with a pipe in-between (IPs made up) 134.27.128.0 | ...
103
votes
6answers
121k 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 ...
4
votes
2answers
76 views

Is it possible to escape quotes within escape quotes within escape quotes within escape quotes?

I'm guessing someone will tell me I'm doing something wrong and dumb and noobish, but I'm trying to script something in the most straightforward method possible and use sudo commands to do something ...
2
votes
3answers
59 views

reverse cat files order

I need to do log analysis and I am facing problem that cat access.log* display latest log file first. I tried to sort logs which takes a lot of time because I have logs from couple of years back. And ...
10
votes
7answers
20k views

How to read first and last line from cat output?

I have text file. Task - get first and last line from file after $ cat file | grep -E "1|2|3|4" | commandtoprint $ cat file 1 2 3 4 5 Need this without cat output (only 1 and 5). ~$ cat file | ...
-2
votes
3answers
44 views

Execute the shell script option by option

I have 3 options create a directory,if exist rename it. copy a directory,if exist in target directory rename it. exit 0 these are the options. in execution time to display this options and there ...
2
votes
1answer
55 views

combine two files to single file with combined columns

I am new to linux/unix shell scripting and struggling to combine two files into a single file with all columns from both files. I am providing my example files. File 1 chr loc T1 C1 chr1 100 2 ...
0
votes
3answers
117 views

get value after specific word

I have this file 1 deiauk David Smith from California 12 58 2 edvin from Nevada 12 5 8 95 2 48 5 3 jaco My Name Is Jacob I'm from NY 5 6 845 156 585 4 from Miami And I need to get values after ...
2
votes
2answers
144 views

How to pass shell variable to an awk search pattern?

In my bash script I have a variable that I am trying to pass to a pattern to search for using awk. However what I expected to happen is not working. I have the following text file (text.txt): ...
0
votes
1answer
44 views

Numeric test in bash: integer expression expected

I created a simple script in bash language to do cleaning of the recycle bin in Ubuntu. here is the script "recycle.sh" #!/bin/bash PUBLIC_PATH="/home/fileserv/.recycle/Public" ##### Clean public ...
0
votes
1answer
15 views

Bash overwrites the first line when using custom PS1 prompt [duplicate]

My question is similar, but different to, this question. I have created a custom PS1 in my .bashrc, as follows: STARTCOLOR='\e[0;36m'; ENDCOLOR="\e[0m" export PS1="\n$STARTCOLOR\u@\h:\! <\t> ...
55
votes
4answers
3k views

Why is `[` a shell builtin and `[[` a shell keyword?

As far as I know, [[ is an enhanced version of [, but I am confused when I see [[ as a keyword and [ being shown as a builtin. [root@server ~]# type [ [ is a shell builtin [root@server ~]# type [[ [[ ...
1
vote
2answers
23k views

“not a valid identifier” when I do “export $PATH”

When I run export $PATH in bash, I get the error not a valid identifier. Why?
10
votes
3answers
23k views

What does $# mean in shell?

What does $# mean in shell? I have code such as if [ $# -eq 0 ] then I want to understand what $# means, but Google search is very bad for searching these kinds of things.
0
votes
3answers
58 views

Delete all files that DON'T have duplicate names?

Given a large list of files, containing the following: FILE1.doc FILE1.pdf FILE2.doc FILE3.doc FILE3.pdf FILE4.doc Is there a terminal command that would allow me to remove all files that do not ...
1
vote
3answers
72 views

Shebang does not set SHELL in cron

I have a script containing: #!/bin/bash printenv When I run it from the command line: env testscript.sh bash testscript.sh sh testscript.sh every time, it outputs SHELL=/bin/bash. However, when ...
0
votes
4answers
59 views

Copying Only Directories With Files

I am trying to copy files and the directory it is in to another location. I can find the path like this: find ~/dim_import/* -type f ! -name xdir | cut -d '/' -f 5-10 which outputs ...
-21
votes
2answers
314 views

Which amongst the given option is TRUE about login shell?

Which amongst the given options is TRUE about the login shell? The login shell varies every time the user logs in. The kernel decides on the availability of the shell during login. The login shell ...
69
votes
5answers
180k views

How do I grep for multiple patterns?

I want to find all lines in several files that match one of two patterns. I tried to find the patterns I'm looking for by typing grep (foo|bar) *.txt but the shell interprets the | as a pipe and ...
1
vote
1answer
22 views

Can I do a delay delivery in Thunderbird or Evolution

Now we have an option of "Delay Delivery" in Outlook. Can we do something like that in thunderbird/evolution or any other linux client ?
42
votes
13answers
13k views

best way to search my shell's history

Is there a better way to search my history file for a command than grep? I do have some idea what the command starts as, but I don't know how far back in the history it is. update: was formerly zsh ...
12
votes
4answers
8k views

How can I kill and wait for background processes to finish in a shell script when I Ctrl+C it?

I'm trying to set up a shell script so that it runs background processes, and when I Ctrlc the shell script, it kills the children, then exits. The best that I've managed to come up with is this. It ...
0
votes
0answers
8 views

lsudo /sbin/ldconfig -v showing Garbage text

RHEL 6.6 When performing "sudo /sbin/ldconfig -v" while trying to follow a different stackoverflow question related to: sudo /etc/init.d/nginx restart /usr/sbin/nginx: error while loading shared ...
0
votes
0answers
30 views

what is scriptname TODAY 0 mean in crontab?

We have some scripts scheduled in crontab with TODAY 0 or YESTERDAY 0 after the script name. What does they mean?
2
votes
1answer
31 views

Secure share in samba not working, why?

The secure share that I created in samba with a password doesn't seem to work. I have the following on my /etc/samba/smb.conf on a Linux Mint box(3.13.0-37-generic) box. [myshare] ...