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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2
votes
1answer
1k views

broken pipe error with popen and JS ffi

I am using a ffi for nodejs which for the most part has nothing to do with this question which is really about understanding pipes better, but does offer some context function exec(cmd) { var ...
3
votes
1answer
109 views

find utility does not recognize bracket notation

I've two files in the current folder: submitWeb.m submit.m the following find does not show the two files: find . -regex .*submit\(Web\)?\.m But the above regex expression works fine in ...
103
votes
5answers
98k 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 ...
3
votes
2answers
36k views

mv: cannot stat No such file or directory in shell script

I wrote a script to move some files form one folder to another folder but I got the following error, I checked 2 folders and notice for 1 folder there are such files and another there is no such files,...
6
votes
2answers
21k views

cat files in current folder and all subfolders [duplicate]

I want to cat a file in current folder and all files in all subfolders (and subsubfolders). Here is my directory structure $ tree . ├── f │   └── foo └── yo I want to cat foo and yo. I've tried ...
-1
votes
2answers
828 views

TAB autocomplete on sudo sh

When I say sudo sh, TAB stops working as autocomplete signal on my Debian. How can I enable TAB key autocomplete after I say sudo sh ?
0
votes
0answers
101 views

unexpected bash behaviour after console login (openSUSE)

I'm trying to install a Linux OS on the computer I use as a home server, because I liked "Raspbian" so much on my Raspberry Pi. I created a custom linux using openSUSE Studio, that's just text based ...
5
votes
2answers
554 views

Passing glob expressions to functions/scripts

The following script is supposed to concatenate multiple csv files in a path specified in the first argument into a single csv file specified in the second argument #!/bin/zsh set -x set -v args=("$@"...
1
vote
1answer
693 views

Getting “zsh: command not found: time” when running `time` in subshell

I installed ZSH (and Oh-My-ZSH) on a Ubuntu 12.10 64 bit machine a few days ago. I just tried to do: time (time ls) and got this error: zsh: command not found: time ( time ls; ) 0.00s user 0.00s ...
3
votes
2answers
7k views

Linux listing files between two date without touch command

I need a command which will list the files between given date and time (YYYYMMDDHHMMSS - format) in to a text file. I don want to use touch command as its creating permission issue. I am new to this ...
23
votes
4answers
8k views

Can't indent heredoc to match nesting's indent

If there's a "First World Problems" for scripting, this would be it. I have the following code in a script I'm updating: if [ $diffLines -eq 1 ]; then dateLastChanged=$(stat --format '%y' /....
3
votes
4answers
12k views

How to know which is the default script shell in Centos?

I'm using Centos 6 and after reading about different shells and dash implementasion as sh replacement in Debian, Ubuntu and Fedora, made up my mind to replace sh with dash as the script shell in ...
3
votes
3answers
2k views

Concatenating thousands of files: > vs >>

I found two seemingly contradictory answers on StackOverflow to the following questions: Concatenating Thousands of Text Files Across Hundreds of Directories (while keeping some structure) How do I ...
29
votes
2answers
1k views

Command line: <<< instead of <<

Why is the command md5sum <<< 'ddd' (output: d6d88f2e50080b9602da53dac1102762 -) right, and md5sum << 'ddd' not? What does <<< mean?
7
votes
4answers
970 views

How to make `cd dir/filename` take me to dir/?

I would find it very convenient to be able to use cd with a file argument. cd myDirectory/anyname.anyExtension would be equivalent to cd myDirectory/ What would be the best alias or function to ...
11
votes
2answers
12k views

What does the tilde (~) mean at the end of a filename? [duplicate]

What is the file with the ~ at the end of the filename for? $ ls # aliased to add flags -rwxrwxr-x 1 durrantm 2741 May 16 09:28 strip_out_rspec_prep_cmds.sh~* drwxrwxr-x 13 durrantm 4096 May 16 14:...
1
vote
1answer
380 views

How to open all the files in a directory, using terminal, in emacs?

I've 4 java files in a directory, which I want to work with in emacs. How do I open them all with one command?
3
votes
3answers
747 views

Print process ID (PID) of a Matlab instance

To run my Matlab scripts, I've created a shell script to which I give two parameters - the path to the matlab file ($1) and to the log file ($2): nohup time matlab -some_parameters -r "run $1;exit" &...
1
vote
2answers
134 views

At init, run my own script instead of the shell

This is purely theoretical but suppose I would like to deploy a linux distribution on many servers. The only solution I can think of would be to create an initramfs with a custom script to perform ...
0
votes
1answer
77 views

Weird behavior when sourcing .zshrc

I'm using zsh 5.0.2 (x86_64-apple-darwin12.3.0) on the latest MacOSX. If it makes any difference, I have also enabled oh-my-zsh. The shell seems to be missing the .zshrc file when I want to source it....
2
votes
3answers
5k views

How to escape a single quote? [duplicate]

This works fine: sed -i 's# @driver.find_element(:xpath, "//a\[contains(@href,##' temp_spec.rb against a source of @driver.find_element(:xpath, "//a[contains(@href,'change_district')]").click ...
5
votes
4answers
834 views

sed how to substitute when string has “http://” in it?

I have a file xx that has the following contents: @base_url = "http://dmstaffing-stage.herokuapp.com/" I want to use sed to eliminate this line (replace with nothing). I have used this sed ...
3
votes
0answers
203 views

Fork vs. thread system time [closed]

I got the following logs: Program 1: Taken from a program executed 64 fork calls: real 0m0.023s user 0m0.068s sys 0m0.008s Program 2: Taken from a program executed 64 thread calls: real 0m0.613s ...
1
vote
1answer
7k views

gunzip multiple compressed files to another directory without deleting the .gz files

I have multiple .gz file in a folder and I want to unzip it in other folder through gunzip without deleting parent file. Please help.
0
votes
2answers
118 views

Is there a general command to see what shell is running? [duplicate]

On some the shell can be read on in the command prompt, other can be seen when help is ran. But this are not covered by all the shells. Is there a general command to see what shell is running?
4
votes
1answer
217 views

Ignore files for zsh's completion for SVN

I managed to configure zsh such that it does not suggest LaTeX temporary files when I use autocompletion for emacs by adding this line to my ~/.zshrc: zstyle ':completion:*:*:emacs:*:*files' ignored-...
4
votes
6answers
1k views

How do I specify arguments to return all dot files, but not . and ..?

Normally dot files are not included for wildcard expansion: % echo * Applications Desktop Documents Downloads Library Movies Music Pictures Public bin If I explicitly ask for dot files, I get them: ...
22
votes
4answers
10k views

Why do I have to re-set env vars in tmux when I re-attach?

I mainly work on a mac and ssh/tmux attach to a Linux machine to do my work. I have ssh-agent running on the Linux machine. I have set -g update-environment "SSH_AUTH_SOCK SSH_ASKPASS WINDOWID ...
6
votes
1answer
3k views

How can I keep color codes with grep input?

If I use two consecutive grep commands, e.g.: echo "foo bar" | grep foo | grep bar Then the first pattern ("foo") is not highlighted. In fact, it seems that grep removes color codes from its input. ...
1
vote
3answers
1k views

Different “history” command output after reconnecting via SSH

Why do I get different results for the "history" command for the same user after I reconnect a disconnected SSH session? I connect to a server using putty (SSH), say as root My network gets ...
3
votes
3answers
672 views

Forcibly create directory hard link(s)?

I understand the reasoning why nearly every unix version doesn't allow hard-linking of directories (in fact HFS+ on OS X is the only one I know, but even that isn't made easy to do yourself). However, ...
10
votes
4answers
2k views

Why does “$(( ~33 ))” produce -34?

$ echo $(( 255 )) 255 $ echo $(( 33 )) 33 $ echo $(( ~33 )) -34 $ echo $(( ~255 )) -256 $ and my kernel is: $ uname -a Linux HOSTNAME 3.2.0-40-generic-pae #64-Ubuntu SMP Mon Mar 25 21:44:41 UTC ...
2
votes
1answer
3k views

redirection to file issues with nohup and pipe

For the following command: ssh -t esolve@hostname 'sudo nohup bash -c "ls > log 2>&1 &"' I always got error information: nohup: ignoring input and appending output to `nohup....
3
votes
2answers
213 views

how to initialize `/etc/group`?

After editing /etc/group, How this update starts functioning without restarting the system in Unix? Is there any command we need to run?
38
votes
7answers
7k views

why does ls -d also list files, and where is it documented?

when specifying ls --directory a* it should list only directories starting with a* BUT it lists files AND directories starting with a Questions: where might I find some documentation on this, ...
6
votes
2answers
1k views

Wait for a X window to appear/disappear (in a sane way)

Inside a shell script, I need to wait for a window that has a string on its title to appear, do some action, and then wait for it to disappear, and do some other action. Until yesterday, I had this ...
2
votes
3answers
826 views

Log in with specific shell at terminal login

If I log in to a system over ssh, I can use the default shell with a simple ssh user@host, or specify something like ssh user@host 'bash --norc --noprofile' or ssh user@host ksh. Is it possible to ...
2
votes
1answer
236 views

File no longer available when trying to edit in vim via <()

When working with mercurial, I frequently do things like vim <(hg cat -r 42 somefile) However, if I try this with a file larger than several hundred lines, I get a Read Error in vim, and only ...
2
votes
1answer
255 views

What does “${x%% *}” mean in sh? [duplicate]

I just saw "$${x%% *}" in a makefile, which means "${x%% *}" in sh. Why it is written in this way ? how can a makefile detect whether a command is available in the local machine? determine_sum = \ ...
3
votes
3answers
9k views

How to move all files with a certain file extension from subdirectories to a single directory

I have a directory that contains many subdirectories. The subdirectories contain lots of types of files with different file extensions. I want to move (not copy) all the files of one type into a new ...
2
votes
2answers
947 views

shell script to do some text manipulation of text file data structure and slight content changes

Apologies in advance for the wall of text, not sure how else to represent the existing data structure. I have been handed about a years worth of logs collected every hour from a server. Sadly, ...
3
votes
2answers
403 views

How to make sure the shell builtin echo is invoked so that its not visible in process list?

Is this going to be visible in the process listing if the below line is executed from a command line or a shell script bash -c "echo $password" or i just need to do echo $password from within ...
2
votes
1answer
97 views

process continous output of synclient

I am using synclient to track the position of finger on the touchpad. I use the following command. synclient -m 100 | awk '{print $2,$3}' This command gives the 'x' and 'y' co-ordinate on the touch-...
6
votes
2answers
572 views

Decode Flags for Kill Command

I am new to Shell Scripting. I saw this Command on a Book for Linux shell Scripting $ kill -HUP 1234 >killout.txt 2>killerr.txt I know what the command does, but i am not able to understand ...
1
vote
1answer
210 views

Standard I/O File Descriptors

I am new to Shell SCripting I code this $ ls -l 1> stdout.txt and I get the output as desired, 1> stdout.txt redirects the output from standard output to the file stdout.txt. I don't ...
2
votes
0answers
163 views

zsh: Echoing every statement?

I have an odd problem with zsh when I switch between shells in a particular way: Option 1 (works well): I start a zsh shell. I switch to tcsh with /bin/tcsh, and I switch back to zsh with /bin/zsh ...
3
votes
3answers
618 views

Including sub-parameters in help options to execute wisely without getopt or getopts?

I am writing a script which can choose a file and print specific content. For example, san#./script.sh Expected Usage : ./script.sh --file1 --dns (Here it checks for file1, search for dns name and ...
3
votes
3answers
899 views

How to open process substituted file from php?

Here's what I tried to do myself: $ type 1.sh #!/bin/bash -eu php -r 'var_dump(file_get_contents($_SERVER["argv"][1]));' -- <(echo 1) $ ./1.sh PHP Warning: file_get_contents(/dev/fd/63): failed ...
25
votes
2answers
65k views

Can I redirect output to a log file and background a process at the same time?

Can I redirect output to a log file and background a process at the same time? In other words, can I do something like this? nohup java -jar myProgram.jar 2>$1 > output.log & Or, is that ...
4
votes
1answer
60 views

Suspend and edit previous single line commands

Say I want to modify the latter of some concatenated command line options, is it possible without killing the first command? Specifically I have compile and run scripts executed thusly: > compile ...