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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116 views

about executing a python program in a shell script which is scheduled on crontab

i have a problem with regards on crontab. I have a script named checker.sh and i want to schedule it that would run every minute: * * * * * sh /home/pi/checker.sh so i have the script here: the ...
7
votes
1answer
162 views

Cannot cd into a directory, no visible problem

I've tried searching and couldn't find a similar scenario. I have a directory into which I cannot cd: # cd /var/log # cd apache2 bash: cd: apache2: No such file or directory # ll -d apache2 ...
16
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11answers
2k views

“Bookmarks” for bash

Navigating several layers of nested directories is often a pain. On Firefox, it is easy because they have bookmarks. So what I'd like to do to bookmarks a file is to type: $ go --add classes ...
5
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2answers
2k views

Read multiple lines from text files in bash

When I am shell scripting, the majority of what I am doing is wrapping the I/O of other modules in python, matlab, etc. To do so, I usually use text files or something of that nature with the ...
0
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2answers
63 views

How to find and replace only a particular word (which is at the end of the file) using shell command?

File1: Dms 01.01.2015 feeder1 6kv close at 04:30 Updated Dms 01.01.2015 feeder1 6kv open at 06:20 Updated Dms 04.02.2015 feeder10 6kv close at 17:23 Updated Dms 04.02.2015 feeder12 6kv ...
5
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3answers
429 views

Why does this one-liner fail to produce output? [duplicate]

The following produces nothing in bash: while true ; do upower -d ; sleep 1 ; done | grep percentage | uniq I've discovered that it doesn't matter what the last- or even the second to last- program ...
7
votes
4answers
8k views

In a regular expression, which characters need escaping?

In general, which characters in a regular expression need escaping? For example, the following is not syntactically correct: echo '[]' | grep '[]' grep: Unmatched [ or [^ This, however, is ...
0
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1answer
239 views

How to implement command history in Linux terminal?

I am using Putty as Terminal to connect a Linux server running Oracle Linux. To use a command multiple times, I have to type that command each time. There is no function of Up and Down button unlike ...
2
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2answers
442 views

How do you add a bash script to your PATH variable using symlinks?

I run a gaming server called PocketMine. So basically I have a folder in my home directory that has a bash script to run the server: ~/PocketMine/start.sh Everytime I want to run the server I either ...
1
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2answers
105 views

Rename file containing spaces and punctuation marks

Someone in our Global Linux 3.0.31-0.9 server has put a file with several spaces, parenthesis, question mark and a colon in its name. And I am at my wit's end to rename or remove it! Sample of the ...
3
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1answer
1k views

what is the use of “export” command

I created a environment variable in one terminal window and tried to echo it in another terminal window. That displayed nothing. $TEST=hello After that I exported it and tried again to echo it in ...
3
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3answers
845 views

How to set HOSTNAME in zsh?

In bash, which sets $HOSTNAME for you, I was able to calculate the total length of prompt line simply by using something like: PS1_length=$((${#USER}+${#HOSTNAME}+${#PWDNAME}+12+${#PS1_GIT})) It was ...
0
votes
1answer
275 views

How to use output from openssl encryption routines in a pipe?

openssl manual claims that openssl enc uses standard output by default. But something is not right with the standard output when decrypting a file. Piping the output to any application such as grep, ...
5
votes
3answers
376 views

How to display commands in a different terminal?

I have a raspberry pi with a screen attached to it. It boots up to a login prompt. I have no keyboard and no mouse attached to it and would like to keep it this way. I proceed to login to it via ssh ...
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votes
1answer
279 views

What command would I issue in order to complete this question?

So I have tried over 10 different attempts and I'm just stumped Here are two inverted-tree diagrams. Issue a command to change the left diagram to the right diagram. Assume that you are in your home ...
7
votes
4answers
1k views

Why doesn't SIGKILL terminate a stopped program (yes)?

I'm using Ubuntu 14.04 and I'm experiencing this behavior I can't seem to understand: Run the yes command (in the default shell: Bash) Type CtrlZ to stop yes Run jobs. Output: [1]+ Stopped yes ...
0
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2answers
182 views

Adding a new directory to PATH vs. a symlink for directory already in PATH

In setting it up so I could execute Sublime Text from bash, I discovered two methods of doing this via different tutorials: Method 1) Create a symlink from /usr/local/bin/subl to Sublime's bin dir: ...
5
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8answers
4k views

How do I delete the first n lines and last line of a file using shell commands?

I have a file named Element_query containing the result of a query : SQL> select count (*) from element; [Output of the query which I want to keep in my file] SQL> spool off; I want to ...
1
vote
1answer
493 views

piping commands after a piped xargs

HP-UX ***** B.11.23 U ia64 **** unlimited-user license find . -type d -name *log*|xargs ls -la gives me the directory name(the ones which contain log in the directory name) followed by all files ...
1
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4answers
241 views

Unix bash/ksh : Selection of first non space character from file from specific line

I have file file1.txt whose contents are as follows: Date List ----------- Quarter Date Year Date Month Date Now I want to read the non space elements from each row of ...
1
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1answer
385 views

Recover deleted commands from history?

If someone were to delete commands from the shells history, is there any way to recover those deleted commands in Linux?
1
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1answer
131 views

TTY control characters sent to stdin of sh doesn't work

I tried to develop a remote app that launches sh and resends an incoming data there, and found that some special sequences don't work. So, for testing purposes, I launched on my desktop sh, then ...
0
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0answers
20 views

Setting X display giver no protocol error [duplicate]

Here is the command i use DISPLAY=:0.0 sh /var/log/show_report.sh & disown This shell script just invokes the browser and here is error i receive No protocol specified Error: cannot open ...
30
votes
2answers
60k views

How can I execute local script on remote machine and include arguments?

I have written a script that runs fine when executed locally: ./sysMole -time Aug 18 18 The arguments "-time", "Aug", "18", and "18" are successfully passed on to the script. Now, this script is ...
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1answer
31 views

Copying all same files to one location and changing the file name to subdirectory_filename

I have conf.yml files in different folders as below. /var/loyalty-badge/conf/conf.yml /var/loyalty-level/conf/conf.yml /var/promotion/conf/conf.yml /var/featured/conf/conf.yml Now I want all the ...
0
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1answer
259 views

How to capture the output of the strings command? [duplicate]

How do I capture the output of the strings command into a .txt file from the command line?
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4answers
518 views

Extract paragraph separated with *** using AWK

I have a file like below: blablabla blablabla *** thingsIwantToRead1 thingsIwantToRead2 thingsIwantToRead3 blablabla blablabla I want to extract the paragraph with thingsIwantToRead. When I had to ...
1
vote
1answer
149 views

Upload from shell to HTTP Server

I use scp command to upload file from my local computer to my ftp server is there any tools to do the same thing with http server (like Apache server ) like scp do ?
6
votes
5answers
3k views

Deleting files with spaces in their names

I am trying to delete all the files with a space in their names. I am using following command. But it is giving me an error Command : ls | egrep '. ' | xargs rm Here if I am using only ls | egrep '. ...
1
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1answer
51 views

Sorting in reverse numeric order on subfield in a multi-field sort

I'm trying to use GNU sort on a directory/file listing, eg (subset of much longer listing): exams2008/Zoology/Summer/ZY4019Sum08.pdf exams2009/Zoology/Summer/ZY4019.pdf ...
21
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9answers
5k views

Find files whose name is 4 characters long [duplicate]

I would like to find files whose name has only 4 characters. Example, there are three files under /tmp: $ ls /tmp txt file linux Output should only show file because it only has 4 characters.
3
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4answers
330 views

Touching issue: Creating a filename from 2 variables

I am trying to create a filename from 2 variables. This is the error msg: touch: cannot touch `/root/tinstalls/2--06/06/15': No such file or directory 2--06/06/15 19:54 This is the code: ...
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4answers
101 views

How to print last few contents in a line?

I have a file that has lines shown below, ta=/*92/*39/*1/*649/*12 ta=/*92/*12/*4/*342/*90 ta=/*92/*33/*9/*455/*3 ta=/*92/*12/*3/*649/*25 ta=/*92/*99/*7/*649/*7 and so on. I want a file that will ...
2
votes
3answers
958 views

Using sed command to find the first occurrence of the pattern and append

Say there is a text file as below: Hello world types="" Mario types="Game" All I want to do is find the first occurrence of type="" and append with word program My desired output: Hello world ...
3
votes
2answers
136 views

Check if conditional with awk for matches in logfile

I want to check the auth.log file for accepted sshd connections and execute an action if any are found. Here is my code: tail -f /var/log/auth.log | awk '{ if($0 ~ /sshd/ && $0 ~ /Accepted/) ...
0
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4answers
1k views

Get process elapsed time in seconds

Similar to How to check how long a process has been running?, I am trying to get the elapsed time for a process in seconds in an embedded Linux system using BusyBox and sh (not bash). The difference ...
15
votes
3answers
1k views

Issue an error when using empty shell variables

Sometimes I use, $PROJECT_HOME/* to delete all files in the project. When the environment variable, PROJECT_HOME is not set (because I did su and the new user doesn't have this environment variable ...
3
votes
2answers
291 views

Substitute for loop variable in a string pattern

I am trying to iterate over an array of file names and substitute the file name inside an absolute path. The code is, #!/bin/bash jsArray=(moment.js datatable.js jquery.js jquery.tmpl.js dt_jq_ui.js ...
3
votes
3answers
6k views

Use config file for my shell script

I need to create a config file for my own script: here an example: script: #!/bin/bash source /home/myuser/test/config echo "Name=$nam" >&2 echo "Surname=$sur" >&2 Content of ...
0
votes
0answers
50 views

Unable to execute root commands using client-connect option openvpn

I'm using the openvpn option client-connect to run a script when a client connects. The scrit works fine when I use simple commands but when I add commands that need root privileges it doesn't work ...
6
votes
1answer
972 views

Are there problems with hyphens in functions, aliases, and executables?

In my testing (in Bash and Z Shell), I saw no problems with defining functions or aliases or executable shell scripts which have hyphens in the name, but I'm not confident that this will be okay in ...
0
votes
3answers
379 views

Can a command be executed without a shell?

I am developing a binary executable program command to execute programs and return the output into a text field. The parameters to the command involve the command itself as it would be typed on the ...
1
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0answers
34 views

Is there any reason to prefer [[ over [ in bash? [duplicate]

I used to think [ would spawn /usr/bin/test and [[ was a builtin, but apparently, it doesn't: $ strace bash -c " [ -z "$FOO" ] && echo yes " 2>&1 | grep test and $ type [ [ is a ...
15
votes
6answers
4k views

How do I recursively check permissions in reverse?

There's a command, I think it comes with apache, or is somehow related to it, that checks permissions, all the way down. So if I have /home/foo/bar/baz it will tell me what the permissions are for ...
7
votes
3answers
4k views

Assigning exit code to a shell local variable

#!/bin/bash function0() { local t1=$(exit 1) echo $t1 } function0 echo prints empty value. I expected: 1 Why doesn't t1 variable get assigned the exit command's return value - 1?
3
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3answers
179 views

Output to stdout works, fails when redirected to a file or a fifo

I have a Wifi antenna and I want to optimise it's position. For that propose I'd like to visualise the current latency in real time. I wrote a one-line script to output the ping latency: lat.sh: ...
1
vote
1answer
61 views

Activate PHP commands on login

Everytime I login into my centOS box. I need to run source /opt/rh/php54/enable to be able to run php commands. What do I need to do to my installation for this to work without running this command? ...
2
votes
5answers
330 views

Get Comma Delimited List of Initials of Items in Directory?

How can I generate a comma-delimited, case-insensitive list of the first characters of the names of the files and directories in a directory, excluding initial "." items, without duplicates? I don't ...
0
votes
2answers
309 views

sponge from moreutils - what's the difference to shell redirect? useful examples?

> brew install moreutils ==> Downloading https://homebrew.bintray.com/bottles/moreutils-0.55.yosemite.bottle.tar.gz ...
3
votes
3answers
135 views

Local `set -e` for functions

Is there such a feature or can it be emulated reasonably easily? I want the same behavior except it should return where set -e would have caused a call to exit.