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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11
votes
4answers
19k views

Difference between ls -l and ll?

I'm relatively new to programming as a whole and some tutorials have been telling me to use ls -l to look at files in a directory and others have been saying ll. I know that ls is a short list, but ...
35
votes
7answers
3k views

Is `~/Documents` a relative or an absolute path?

This is merely just a vocabulary question, but which keeps turning around in my head. It comes from a practice exam from a LPIC preparation book. The correct answer according to the book is that ...
-1
votes
2answers
66 views

How do I take a prompt response and send it to a text file?

I'm new to shell scripting and I need help I want to ask the user what is their ORACLE_SID, ORACLE_HOME, and then send the output in a file. I want to create a param file that has ORACLE_HOME= ...
0
votes
0answers
36 views

Concatenating two strings cuts string

I extract two numerical strings from a textfile and and want to combine them to create a new string. The new string will be a filename. This is the textfile dates.dat: 378464,2015-01-31 ...
0
votes
1answer
38 views

.sh script error issues

I have a sh script with which I connect to postgres DB and execute a psql command. The script is as shown below: /opt/postgres/9.2/bin/psql pcwh -U pcwhuser << EOF \i ...
3
votes
3answers
119 views

Print man pages with fixed width

With the example command man apropos > outputfile a text file is generated which contains the formatted man page of apropos (with some little differences with respect to man apropos directly ...
3
votes
5answers
1k views

How to read certain lines after a find some text?

How i can read a certain number of lines after find some text? Eg.: Read next 2 lines after find "Unix" on: Test 1 Test 2 Test 3 Test 4 UNIX Test 5 Test 6 Test 7 Test 8 Test 9 Result can be: ...
1
vote
2answers
59 views

Odd syntax for ssh and bash to run command

I'm pretty new to shell/bash scripting and I'm writing a script on OSX to automate some rather tedious efforts. I'm trying to run a portion of my script on a remote host using ssh. There's a common ...
1
vote
1answer
62 views

How to execute a for loop in bash as a string

I need to execute a loop as a string. This: bash -c "for l in $(/bin/ls /dir1); do /bin/ln -sf $l /dir2/; done" Gives an error: /bin/bash: -c: line 1: syntax error near unexpected token `file1' ...
5
votes
4answers
2k views

How can I search for a file with fixed name length using ls?

In a directory, I have files like lazer_100506 lazer_100707 lazer_091211 lazer_110103 lazer_100406_temp lazer_100622#delete etc How can I get a listing of only the first four files? $ ls ...
2
votes
1answer
42 views

Bash do action as nobody and nogroup?

I have a log file that was created by nobody:nogroup, which is activity being logged to, I wanted to emulate adding a message to that log file. My first though was to: $ sudo su nobody This account ...
0
votes
2answers
16 views

Assigning output of a Dynamic Performance View (v$asm_diskgroup) to a variable in Shell Script

I am trying to assign the output of select name from v$asm_diskgroup; to a variable in Shell . The script is failing because of special character '$' in the table name . Note : While i ...
0
votes
0answers
29 views

Writing a basic shell script [duplicate]

I'm using a cluster and I want to write a start up script to run the commands I have to run at the beginning of every session. My script looks like this #!/bin/sh module add apps/COPASI module add ...
0
votes
2answers
62 views

Display CPU cores usage in percentage without using top

I am using java to run a command on linux. Since top is an interactive command and need to press 1 to get the info of all the cpu(s) so I cannot use that. So I am using the following command to get ...
18
votes
4answers
16k 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
0answers
21 views

To list only the file names in a present working directory using unix shell command [duplicate]

There are some links,directories and files in my path. I want to list only the file names eg. logfile1 redolog1 dumplog1 logfile2 lrwxrwxrwx spsy spec Jun 23 2343243 jpeg --> ~/home/s/jpegs ...
-1
votes
2answers
101 views

How to remove a column or multiple columns from file using shell command?

My file, ARCHIVE B1_NAME B2_NAME B3_NAME ELEMENT INFO_NAM WERT PROCID -------- -------- -------- -------- -------- -------- ---- ------ ...
4
votes
3answers
560 views

Behaviour of “|” pipe in linux with “>” output redirection

I am executing command ls > a.txt | sort > b.txt This command is doing the below things : executing ls sorting it creating a.txt and storing sorted output to a.txt creating b.txt , but its ...
2
votes
1answer
39 views

crontab versus manual running script

I wrote a script to check for wifi connection that has an "if then else" statement. If I run the script manually the "if" statement is 1, as it should, if the crontab runs it automatically the "if" is ...
23
votes
5answers
24k views

Sorting the output of “find”?

I need to be able to alphabetically sort the output of find before piping it to a command. Entering | sort | between didn't work, so what could I do? find folder1 folder2 -name "*.txt" -print0 | ...
0
votes
1answer
39 views

How to get a X line from file1 and Y line from file2 using shell command?

In file 1, 'Server restoration is complete now. It will be operational within few seconds. Please keep all the log file once the restoration is complete.' In file 2, 'Restoration was successfully ...
15
votes
3answers
786 views

Can I make a public directory under a private directory?

I have a personal folder /a/b on the server with permission 700. I don't want others to list the contents in /a/b. The owner of /a is root. Now I need to open the full authorities of directory /a/b/c ...
0
votes
2answers
31 views

Copy file,create duplicates in different directory with predefined list of filenames

I have a file rock.mpg in the folder directory /folder1/folder2. I need to create multiple (340) duplicate copies of this file in a different directory say /folder1/folder2/folder3 but with different ...
165
votes
11answers
62k views

Turn off buffering in pipe

I have a script which calls two commands: long_running_command | print_progress The long_running_command prints a progress but I'm unhappy with it. I'm using print_progress to make it more nice ...
0
votes
2answers
54 views

To add line numbers in every line using shell command?

My file, PSS-A (Primary A) PSS-B (Primary B) PSS-C (Primary C) PSS-D (Primary D) PSS-E (Primary E) PSS-F (Primary F) PSS-G (Primary G) PSS-H (Primary H) PSS-I (Primary I) SPARE ...
-1
votes
1answer
37 views

How can I delay the evaluation of variables (lazy evaluation)?

For example, I create 32768 directories named 0,1,2,...32767. I want to randomly choose one as the path every time I run a command. So I change $PATH to $PATH:/blabla/$RANDOM, but it won't work ...
1
vote
2answers
33 views

unable to login via tty{1-6} as a normal user

Unable to login via tty{1-6} as a normal user. Can only login as root. When logged in with normal user it displays the greeting message from /etc/motd and logs out immediately. What could be the ...
11
votes
7answers
2k 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 ...
-1
votes
1answer
24 views

Assign regular expression as character for a variable

I am wondering is there is a way to assign a regular expression as a character in a string to a variable and not have the regular expression change my variable. For example: in my directory I am ...
1
vote
3answers
9k views

tar: Unexpected EOF in archive

I am trying extract .tar.gz file it but with no luck gzip: stdin: unexpected end of file tar: Unexpected EOF in archive tar: Unexpected EOF in archive tar: Error is not recoverable: exiting now the ...
2
votes
2answers
877 views

Autocompletion for Makefile rules in tcsh

I'm using tcsh in a SUSE 11 box and I realized that when typing makeTab it allows me to auto-complete the rules available within the Makefile, not the files that are inside the current directory. ...
2
votes
0answers
30 views

Restrict a user from viewing other user's processes [duplicate]

Suppose there are two users : user1 & user2. Now we know that if I give top -u user1, I can see only the process respective to user1. But if I do top -u user2, I can see all the process running ...
4
votes
1answer
166 views

Any problem assigning one variable to another in shell without using quotes? [duplicate]

This question is about assigning the entire contents of one variable to another variable. Variable is not being used (sent to echo, etc.) No parameter expansion is being done during the assignment. ...
10
votes
2answers
18k views

Why is my find not recursive?

I am running the following command, but it is not performed recursively: find . -name *.java I know there are java files further down in the current directory but it is performing the find on the ...
2
votes
1answer
90 views

arithmetic syntax error in string compare

I have written a shell script which takes file name as parameter e.g user/test.txt. I want to make this file parameter optional if user does not wish to provide file name he/she can give as "None" ...
16
votes
8answers
5k views

How to pipe output from one process to another but only execute if the first has output?

How can I rewrite this command to only email if there is output from the mailq | grep? mailq | egrep 'rejected|refused' -A 5 -B 5 | mail -s 'dd' email@email Is this even possible on one line?
2
votes
3answers
742 views

Redirect stderr to a file, but create only if any stderr happened? [duplicate]

I'm running a command like: parallel --spreadstdin --line-buffered 'some_command 2> `mktemp --tmpdir /tmp/stderr`' | do_something The trick is that parallel creates a lot of processes and they ...
-1
votes
2answers
65 views

Executing script after error

I want to continue execution of shell script even after error in particular step, but it is getting terminated after error if [ condition ];then cmd else cmd1 return 4 fi cmd2 I ...
4
votes
1answer
48 views

Where to save temporary files for shell scripts

I have a script to toggle my screen backlight (mapped to a keyboard shortcut), and I want to save the brightness level so I can restore it when pressing the keyboard shortcut again. Is there a ...
2
votes
4answers
14k views

Executing a shell command from PHP with shell_exec

Included in my thesis is to create an administration interface, in which an administrator can approve users whom have asked for access to use OpenNebula. Upon approval the users should be added to ...
1
vote
1answer
45 views

Sending command to second shell

Let's say I have one command window open, and it's running some Java application, regularly outputting text. If I wanted to send a command to it, I could just type it in and press enter. But how ...
0
votes
0answers
7 views

How do I edit my directory colors in zsh so directories in a network share aren't so ugly? [duplicate]

The display colors of directories located on mounted network shares are horrid: Local directories look much nicer: As I understand it, these settings are set in these lines in .zshrc: eval ...
1
vote
1answer
35 views

Vi mode or emacs mode in the whole system

I use vi mode in zsh, tmux and my favorite text editor (vim obviously). I'm interested to have this behavior in the whole system. I know I can use plugins in firefox, thunderbird, etc. but if there is ...
40
votes
8answers
62k views

How can I get the size of a file in a bash script?

How can I 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?
15
votes
8answers
21k views

How to compare to floating point number in a shell script

I want to compare two floating point numbers in a shell script. The following code is not working: #!/bin/bash min=12.45 val=10.35 if (( $val < $min )) ; then min=$val fi echo $min
-1
votes
2answers
19k views

Redirecting the content of a file to the command “echo”

I have a file named my_file.txt whose content is just the string Hello. How could I redirect its content to the command echo? I know I have the commands less, cat, more... but I need to do it with ...
1
vote
1answer
22 views

Backward and foreward search are inversed with vi mode in zsh

When I enter in vi mode with set -o vi, I enter in command mode, and I touch the key ? it produce a / and the inverse. Is it normal ? How to change this behavior?
0
votes
2answers
35 views

How to run to parallel gnome-terminal windows?

I'm looking to run two independent parallel gnome-terminal windows with some parameters, from 1 shell script. So far I've got this: #!/bin/sh gnome-terminal -e window1.sh & gnome-terminal -e ...
55
votes
3answers
52k views

How do I use pushd and popd commands?

What are the practical uses of both pushd and popd when there is an advantage of using these two commands over cd and cd -? EDIT: I'm looking for some practical examples of uses for both of these ...
0
votes
0answers
10 views

Audio File Search, Count and Sort - OS X or Synology

There is a collection of audio files on a Synology NAS. Approximately 24,000 albums worth, that I need to analyse and report on. I will need to: Count total number of files Count types of files ...