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)

0
votes
1answer
13 views

how to concatenate Login, pwd and @server variables?

how to concatenate Login, pwd and @server variables ?? ex: export Login_va="Login" export pwd_va="pwd" export server_var="@server" echo whenever sqlerror exit | sqlplus ...
23
votes
4answers
18k views

How to Execute multiple command using nohup

I need to execute multiple commands using nohup. Each command should be executed after the previous command. I used this command as an example: nohup wget $url && wget $url2 > /dev/null ...
3
votes
5answers
989 views

What does pwd return?

Does the command pwd in a shell script return the directory the shell script is in?
2
votes
3answers
123 views

Why are non-environment variables passed to the subshell invoqued by command substitution?

Bash manual says: Command substitution, commands grouped with parentheses, and asynchronous commands are invoked in a subshell environment that is a duplicate of the shell environment, except ...
0
votes
0answers
18 views

Delayed Expansion

I wanna make a quine .sh script, and this is what I've made so far: quine.sh: #!/bin/sh q="#!/bin/sh\nq=$q\necho \$q" echo $q Focus on this line: q="#!/bin/sh\nq=$q\necho \$q" At the first ...
2
votes
2answers
53 views

Is a sub-shell the same thing as a child-shell

There are this two names: a subshell and a child-shell. Yes, a child process will be started by any of this: sh -c 'echo "Hello"' ( echo "hello" ) echo "$(echo "hello") echo "hello" | cat Are all ...
0
votes
1answer
27 views

How to hide Login/Pwd into shell?

I've a Shell script(.run) that let me to connect into Oracle sql : echo whenever sqlerror exit | sqlplus Login/Passwd@SERVER @"TABLE1.sql" echo 'return code : ' $? I'd like to hide ...
1
vote
2answers
19 views

What is the default memory allocation for shell process by linux

What is the default memory allocation for shell process by Linux , i mean is there any upper limit for shell process or any process.
1
vote
4answers
111 views

Split comma separated list ignoring commas within matching {}

I want to split a csv, but ignore any commas within matching curly brace groups, and loop through each of the list members. The code below works great but does not consider commas within curly brace ...
0
votes
3answers
21 views

How to bulk compress different sub-folders?

I have a folder all_folders which contains 5 folders: ./all_folders ./all_folders/folder1 ./all_folders/folder2 ./all_folders/folder3 ./all_folders/folder4 ./all_folders/folder5 Can I compress all ...
234
votes
2answers
63k views

Difference between nohup, disown and &

What is the difference between $ nohup foo and $ foo & and $ foo & $ disown
0
votes
2answers
25 views

How to read a file into a shell script as a variable?

I need to write a shell script to read a text file in and perform operations on it to count all distinct words in the text file. I have all of the commands needed to do these operations, but how ...
0
votes
1answer
22 views

nohup nice job aborted when disconnected

I've learned that "nohup" command allows the command to keep running if you lose your connection or need to logout. I'm running "nohup nice my command &" in remoter through shh, and after my lap ...
0
votes
1answer
18 views

Comparing 2 directories and copying the different sub-directories to a 3rd directory

I have 2 directories DIR1 and DIR2 DIR1 is base directory, where new changes come often, sometimes new sub-directories as well. DIR2 has older version of files. I want to compare these 2 ...
1
vote
1answer
21 views

Remove forced line breaks from fortune output while preserving them for the author line

Recently I encountered the great fortune command and use it now to send a nightly quote to a persistent chat. Now I wonder how to remove the forced line breaks for the quote part, but preserve them ...
36
votes
5answers
65k views

Script to monitor folder for new files?

How do I detect new files in a folder with a bash script? I would like to process the files as soon as they are created in the folder. Is this possible to do so or do I have to schedule a script with ...
-3
votes
2answers
42 views

How to achieve using ls command [on hold]

I have two files in a directory: abc_160101.txt and abc_a_160101.txt. How to list the first file only with ls command using abc_* or other pattern?
16
votes
4answers
29k views

Pass shell variable as a /pattern/ to awk

Having the following in one of my shell functions: function _process () { awk -v l="$line" ' BEGIN {p=0} /'"$1"'/ {p=1} END{ if(p) print l >> "outfile.txt" } ' } , so when called as ...
1
vote
1answer
36 views

Remove a part of a path from a variable content

In a Bash I have a variable: LOCAL_PATH="/this/is/a/path/" Then I have another variable, which content starts with LOCAL_PATH and it should be removed: LINE="/this/is/a/path/which/is/longer" The ...
0
votes
1answer
27 views

Print lines not containing a Tab

I have a text file (around 15000 lines) that is supposed to contain two fields separated by a Tab in each line. Is there a way to display the lines that do not contain a Tab separating the two ...
0
votes
2answers
50 views

command not found error after giving permission to access file using chmod

I've been trying to run a script using chmod. Here's how I tried to execute the script: $ chmod u+x tester $ ./tester ./tester: Command not found. I always get the Command not found error and I'm ...
30
votes
4answers
35k views

How to attach terminal to detached process?

I have detached a process from my terminal, like this: $ process & That terminal is now long closed, but process is still running and I want to send some commands to that process's stdin. Is ...
20
votes
7answers
1k views

How could I remember how to use redirection?

I know what program > /dev/null 2>&1 does. It redirects the output to /dev/null and 2>&1 means to redirect the error output in the same place where the output is sent. My ...
0
votes
1answer
32 views

How do i call the case function

I have the following script to login to the servers. This scripts enables me to login to the host automatically using expect script based on the option i choose. As soon as i logout from the host im ...
-4
votes
1answer
43 views

Simple bash script to print prime numbers from 1 to 1000 [on hold]

How can I make a POSIX script that will print all the prime numbers from 1 to 1000? Lots of thanks
-1
votes
1answer
51 views

meaning of [ $? -ne '0' ]. (shell script)

could anyone tell me what the following command means? I'm reading a shell script and studying what it does. But at the end of the script, the following commands appeared. I have no idea what it ...
58
votes
11answers
66k views

How do I convert an epoch timestamp to a human readable format on the cli?

How do I convert an epoch timestamp to a human readable format on the cli? I think there's a way to do it with date but the syntax eludes me (other ways welcome).
16
votes
9answers
29k views

Generate random numbers in specific range

After googling a bit I couldn't find a simple way to use a shell command to generate a random decimal integer number included in a specific range, that is between a minimum and a maximum. I read ...
1
vote
1answer
960 views

Shell Script Help - Automatically assign users to group

Recently, I have just started to learn linux and I am currently trying to make a shell script that can automate the task of creating user accounts, assigning them passwords and then assigning them to ...
1
vote
1answer
37 views

linux unbuffered compression options

I'm working on a embedded system and due to persistent memory restrictions, I need to compress a log file "on the fly". My objective is to have a one liner inside a script, which would look like ...
-4
votes
3answers
49 views

Write file names in to a file

In a directory I have X.txt,Y.txt,Z.txt files. I want to move these filenames into a single file like below: Out_file.txt X.txt Y.txt Z.txt Any unix command to achieve this?
1
vote
1answer
30 views

Comparing original & backup folder, then deleting non-existing files

I'm using Raspbian jessie (ubuntu). I made a .sh that makes a backup .img of everything (excluding mnt, tmp, run, dev, boot, etc.) and let this run once a week with crontab. It checks for modified ...
1
vote
0answers
33 views

Getting Busybox Cron to work on Qemu ARM VM [on hold]

I created a .sh script, then tried crontab -e and entered * * * * * /etc/cronscript.sh, then tried to start it by typing crond. It looks like its trying to do something once per minute, but not my ...
3
votes
1answer
52 views

How to create an alias for two Git commands that use a parameter? [duplicate]

I regularly have to delete a local and remote Git branch. Therefore, I run the following commands: $ git branch -d feature-branch $ git push --delete origin feature-branch Since I mostly execute ...
0
votes
1answer
33 views

Listing files with a certain extension

I'm suppose to write a command that would list all files that end in .tx with an optional t at the end. So far all I got is listing the files that end in .tx which is: ls *.tx Now my problem is ...
1
vote
2answers
636 views

How to rename multiple files using find

I want to rename multiple files (file1 ... filen to file1_renamed ... filen_renamed) using command find command: find . -type f -name 'file*' -exec mv filename='{}' $(basename $filename)_renamed ';' ...
88
votes
4answers
77k views

How to get the pid of the last executed command in shell script?

I want to have a shell script like this: my-app & echo $my-app-pid But I do not know how the get the pid of the just executed command. I know I can just use the jobs -p my-app command to grep ...
1
vote
1answer
26 views

How to get file descriptor number of a output and how to redirect all of them at once

Lets take this command for example $ time ssh ec2 ls www apps real 0m0.554s user 0m0.004s sys 0m0.000s $ time ssh ec2 ls 1>/dev/null real 0m0.554s user 0m0.004s sys 0m0.000s ...
13
votes
3answers
3k views

How can I redirect `time` output and command output to the same pipe?

Suppose I have a binary called foo. If I want to redirect the output of foo to some other process bar, I could write ./foo | bar. On the other hand, if I wanted to time foo, and redirect the output ...
13
votes
2answers
10k views

How do I time a specific command?

(The linux equivalent of TimeThis.exe) Something like: timethis wget foo.com Receiving foo.com ... wget foo.com took 3 seconds.
34
votes
2answers
15k views

How to run time on multiple commands AND write the time output to file?

I want to run time command to measure time of several commands. What I want to do is: Measure the time of running of all of them added together Write the time output to a file Write the STDERR from ...
1
vote
3answers
36 views

Run a command over directories with name recursively

I have the following directory structure in AIX. codeRepo/REPO1/AREA1/objects codeRepo/REPO1/AREA2/SUBAREA1/objects codeRepo/REPO1/AREA2/SUBAREA2/objects From codeRepo I want to run chown myUser * ...
1
vote
2answers
58 views

Crontab not running a shell script

Using account alex, I created: ~/pocketmine/pocketmine.sh When I manually run this using the same account, alex: cd pocketmine ./pocketmine.sh start It runs fine. I have added this to ...
3
votes
2answers
28 views

Run in background but not discarding the output

I use a Git hosting. So I often run git push. I want to run git push in background, in order that me not to wait when it finishes but do other tasks in my terminal. But I don't want to run git push ...
0
votes
0answers
20 views

meaning of !(something) in shell [duplicate]

While searching for a way to move all files in a dir to one of its sub-folders, i came across mv !(something) something which should do the job - but only in bash. However i could not find why. in ...
1
vote
1answer
47 views

Combining strings command and grep: how to limit results to null-terminated strings

I have a feeling that it is strings which is thwarting my efforts here. The binary files I want to use strings on unfortunately yield several matches per file, even though it is a 100% rule that ...
-1
votes
2answers
42 views

how to login a user using shell script [on hold]

In my computer i have two user(tiger,jenk) now i want to create a shell script for login user "jenk" from user "tiger" i m try this code [tiger@pagaltiger mytask]$ echo -e "IncorrectPassword\n" | ...
0
votes
1answer
35 views

Only send email if disk usages exceeds 80%

My script is: abc=$(df -h | sed s/%//g | awk '{ if($5 > 80) print "Alert "$0;}' | awk '{print $2,$6}') \ && echo -e "Dear All, \n\n$abc\n\nABC" \ | mailx -s "Disk partition" ...
2
votes
1answer
21 views

Get current memory usage of a tmux session

As the title says. I need a way to the used memory of a current tmux session. I am not sure if that is even possible. I am using tmux to start multiple minecraft servers I'd like to know each servers ...
0
votes
3answers
66 views

To calculate average by taking command line argument

The task is that if input numbers: 4 1 2 9 8 Output=(sum of all except first_number_in_series)/first_number in series Then output average should be 1+2+9+8/(first_number_in series)=20/4=5 I have ...