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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8
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3answers
4k views

How can I do the equivalent of tail -f with ls? [duplicate]

Possible Duplicate: Is it possible to follow a command (run repeatedly)? as one would follow a file using tail -f? I would like to monitor files that are being downloaded to a directory in ...
0
votes
2answers
663 views

source script as command [closed]

For some reason (?), often when I write scripts nowadays they do not work, or work only in part, and then I try with . or source and they work perfectly. I'm unsure what is causing this as the scripts ...
2
votes
1answer
728 views

Command substitution: file or command not found

The following script #!/bin/bash QUERY='select * from cdr;' MYROWS=$("sqlite3 -list -nullvalue NULL -separator ',' /var/log/asterisk/master.db '${QUERY}'") gives me ./bla.sh: row 35: sqlite3 -list ...
6
votes
2answers
2k views

What is the best way to find a list of several strings within a large text file

The short, general question is: In Unix/Linux, what is the best way to find a list of several (about 150) strings within a large text file? I am asking this to all Unix/Linux experts as a general ...
4
votes
3answers
2k views

shell script to read from multiple files in parallel

I need to write a script that runs parallel and looks for a string in multiple files. I tried a lot of options but they slow down the speed of my processor.
2
votes
1answer
199 views

How to run a command against all the files of particular types on a filesystem?

I've just recovered tons of files (distributed in a complex directory structure, having very long names, using Unicode symbols, spaces etc in names) from a damaged hard drive. Now I'd like to verify ...
0
votes
1answer
6k views

Script failing with “command not found: ^M”

When I try to run the following script in zsh, via the command /bin/zsh ~/.set_color_scheme.sh I get the following error: command not found: ^M The script has u+x permissions and it used to work on ...
0
votes
2answers
514 views

Installing a shell (e.g. zsh) without being system admistrator [duplicate]

Possible Duplicate: how can I use bash as my login shell when my sysadmin refuses to let me change it Say I have rwx permissions to a directory (my home directory). Can I install a shell ...
3
votes
1answer
601 views

Extract directory from wget's stdout

I am trying to wget a tarball from github.com and, without creating a temporary file, extract a subdirectory from it: wget -qO- https://github.com/django-nonrel/django-nonrel/tarball/develop | tar ...
23
votes
4answers
20k 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 ...
14
votes
3answers
12k views

Can files be created with permissions set on the command line?

When creating directories, mkdir -m <mode> <dir> provides for creating one or more directories with the given mode/permissions set (atomically). Is there an equivalent for creating files, ...
1
vote
1answer
84 views

Social website about shell commands

I remember seeing an entire social website devoted to the question What are your favorite command line features or tricks?, where you can post shell commands, tag them, comment on them, and rate ...
5
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2answers
20k views

Execute shell script from php, as root user?

Need to execute the following line from PHP: $res = shell_exec('sudo sh /home/nicklas/cronjobs/make_account.sh username password'); The problem is nothing happens on execution. If i try to ...
3
votes
1answer
691 views

Shell script to execute a command with iteration

This is a script which looks for .tab files in a folder an should imports them with ogr2ogr, but I fail with the correct bracing. for i in $( ls *.tab ) do echo item: $i ogr2ogr -f PostgreSQL ...
9
votes
3answers
444 views

How can my script know when I'm in a virtual console vs. an xterm?

A few of my scripts (keymap changing, public key adding) need to act differently when in a virtual console vs. in an xterm. What's the real code for #!/bin/ksh if [[ in_a_virtual_console ]]; then ...
2
votes
3answers
554 views

Return value of commands when using stdin?

Imaging I am executing the following command: echo "root:mypass" | chpasswd How can I get the return code / error code returned by chpasswd? Is that possible in this case at all? I tried RET = ...
6
votes
2answers
9k views

Passing arguments with quotes and doublequotes to bash script

At this moment I have: #!/bin/bash screen -p 'ScreenName' -x eval 'stuff '"'"$@"'"'\015' echo eval 'stuff '"'"$@"'"'\015' But when I call my script as: # script.sh asd "asd" 'asd' my arguments ...
1
vote
1answer
545 views

Shell variables not working?

I'm trying to store the date in a variable ($DATE) so I can use it later, but it doesn't seem to work. See anything wrong? DATE=$(date +"%Y-%m-%d %R") sudo mysqldump -u root -pnotgivingyoumypassword ...
-1
votes
1answer
7k views

Bash function to compare two binary files [closed]

I need a function to compare 2 binary files, here the requirements: 2 files, not 3 or 4 files can't be assumed to exist avoid running checksum (CRC/MD5/SHA/...) until one must if running multiple ...
3
votes
1answer
2k views

Is it a bug for join with -t\t?

I have a problem with the command join. "The default join field is the first, delimited by whitespace" (Cited from join --help). However, there is a field containing sentences in my tab-delimted ...
3
votes
1answer
3k views

How to move file based on file name expression using shell script?

I want to achieve the following using a shell script. When a script is called with a file as a parameter, it should move the file based on a portion of its name. For example, "Car insurance ...
3
votes
2answers
2k views

How to pass a variable to an sh child process? [duplicate]

Possible Duplicate: How to “send” variable to sub-shell? I have a bash script and inside that script I do sh. How to pass a variable to the new shell? This is how it is ...
8
votes
5answers
8k views

Check if script is started by cron, rather than invoked manually

Is there any variable that cron set when it's running a program ? If the script is running by cron, I'll skip some parts; otherwise invoke those parts. How can I know if the bash script is started by ...
8
votes
1answer
16k views

Executing a script in zsh - file permissions

I'm confused about execute file permissions not behaving as I expect. Probably because my expectations are wrong. Anyway: I have a script file, for simplicity is just called s, located in ~/bin. For ...
1
vote
5answers
12k views

bash execute read command from file

After some manipulations, I got the file with commands that I would be glad to be able to execute. Input file (name of file is inp2.txt): "02 - Beautiful Emptiness.mp3" "02 - Come. mp3" "02 - Go ...
24
votes
4answers
17k views

how can I use bash as my login shell when my sysadmin refuses to let me change it

The unix sysadmin where I'm working is reluctant to give me access to change my login shell from ksh to bash. He has given various excuses, the funniest being that since they write all their scripts ...
1
vote
3answers
3k views

how to sum output of awk or other expression with xargs

Suppose i have the following bash shell script: #!/bin/bash export count=0; for i in `ls ./mydoc` ;do pdfinfo ./mydoc/$i | egrep Pages |awk {'print $2'} |xargs -+ $count ; ...
3
votes
2answers
3k views

exec < filename - what does this do?

I have found the following code snippet (sh): TESTFILE=$TEST_PATH/test.out if [ -f $TESTFILE ] then exec < $TESTFILE else echo "$TEST_PATH: no test.out file" fi ...
1
vote
2answers
2k views

Have bash script wait for password

I want to write a little script which sets up a socks proxy via ssh and then starts a browser using that proxy. #!/bin/bash ssh -D 1234 user@host #& chromium-browser ...
2
votes
2answers
3k views

Cron to delete particular file(s) from a specific directory

I am new to shell scripting. I am trying to write a cron for unix shell that will delete some files, say after 2 weeks or after 1 month from a specific directory. /somedir1/somedir2/ if(somedir2) ...
2
votes
3answers
3k views

Switching to superuser while shell script is running

I have a shell script that contains the following lines: CURRENT_USER=${USER} echo $CURRENT_USER su echo switch to `who am i` Once the 2nd line is executed, the shell prompts me to enter the root ...
7
votes
2answers
9k views

Why Bash unable to find command even if $PATH is specified properly?

I am specifying path to my command in the file /etc/profile: export PATH=$PATH:/usr/app/cpn/bin My command is located in: $ which ydisplay /usr/app/cpn/bin/ydisplay So, when I performing "echo ...
3
votes
2answers
1k views

Remove 50GB oldest files in busybox when used capacity reaches 95%

Ok i have requested a code here but initial i didn't ask to make it busybox compatible. My bad. I'm new to linux and coding. The code needs to do the following: Delete 50GB of oldest data (dir ...
1
vote
1answer
489 views

show only tags of an xml document on the command line

Is there a command line command or utility I can use to show only the tag structure of an xml document? I looked at xmllint but I didn't see a switch to do it. For a structure like ...
2
votes
4answers
1k views

Get default ubuntu motd in fish shell

I would like to have Ubuntu's MOTD in the fish shell. Ubuntu's default is as follows: That is essentially what I would like to see when open up my terminal (terminator, which loads fishfish) As ...
4
votes
2answers
3k views

Identifying the system package manager

Is there a way (from a script) to identify the default system package manager? To clarify, what I want to do is run a given command and, on Debian or any of its derivatives it'll return something ...
37
votes
2answers
16k 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 ...
10
votes
1answer
340 views

How do you set up the environment for es?

I've been playing with es the last couple of days, and it (like rc) has the quirk/feature that it only runs its startup script (.esrc) on login. The usual way to run code in each interactive session ...
0
votes
1answer
1k views

add directory to shell profile [duplicate]

Possible Duplicate: How can I make a program executable from everywhere So, I'm new to Linux/Unix and am working in a corporate version of Red Hat at my company. Obviously I don't have full ...
10
votes
2answers
1k views

How to set on executable bit for a particular file automatically

I want that when i make create a particular file, suppose i create it in vim editor, the created file should get executable permission as well when it gets created . I want this as i am creating some ...
9
votes
7answers
6k views

How to remove only the content of directories?

I'm in a folder: /var/myfolder. Inside there are some other folders like: /var/myfolder/A/ /var/myfolder/B/ `/var/myfolder/C/ etc. Inside each there are some files with random names. How do I ...
27
votes
1answer
1k views

Why does echo >file use more real time than echo | sed >file?

The example, below, surprised me. It seems to be counter intuitive... aside from the fact that there is a whisker more user time for the echo | sed combo. Why is echo using so much sys time when it ...
1
vote
1answer
4k views

Do shells support recursion?

I'm trying to write recursive functions in my shell scripts. Consider the following code: function printA { if [[ "$1" = 0 ]]; then return else echo "a$(printA $(("$1" - 1)))" ...
3
votes
2answers
310 views

open a file using CDPATH and symlink

To quickly move around, I added a path to CDPATH that contains symlinks to different locations. I did this by adding the following line to .bashrc: export CDPATH=~/symlinks When working with ...
65
votes
4answers
153k views

How to add repository from shell in Debian?

In Ubuntu one can add a repository to apt-get via the following command - sudo add-apt-repository ppa:yannubuntu/boot-repair As Ubuntu is based on Debian code base, I was expecting that the same ...
29
votes
5answers
83k views

Shell script fails: Syntax error: “(” unexpected

I've been working on a script that automates setting up a development environment for Raspberry Pi development (step by step details that work are here). The script is linked in that article but ...
5
votes
1answer
857 views

How can I control an existing remote shell?

On my remote machine, an xterm/shell has been created (by another process). I have full access to that shell through VNC. But really I would like to be using a text mode shell on my local machine. ...
5
votes
1answer
325 views

Handling filenames that contains a hyphen, within a script

I have few files that was incorrectly encoded, during extraction, file names now become something similar to -a -b, Now I'm trying to fix this issue with: convmv -f ENCODING -t utf8 --notest * But ...
13
votes
4answers
118k 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 ...
0
votes
1answer
3k views

How to move file from one folder to another in shell script by changing the permission

I want to move a file from one folder to another folder. When the file's format is with space in between (file _name.dat) and when I am using the command mv file _name.dat /tmp then the file is not ...