Remove last n charecters from a string in Ansible

Question

Below is my playbook that constructs a string.

   - name: Construct command for all paths on a particular IP
     set_fact:
       allcmd: "{{ allcmd | default('') + '\"ls -lrt ' + item.path + ' | tail -57 &&' }}"
     loop: "{{ user1[inventory_hostname] }}"

   - debug:
       msg: "allcmd is:{{ allcmd }}"

Output:

ok: [10.9.9.11] => (item={u'path': u'/tmp/scripts', u'name': u'SCRIPT'}) => {
    "ansible_facts": {
        "allcmd": "ls -lrt /tmp/scripts | tail -57 &&"
    },
    "ansible_loop_var": "item",
    "changed": false,
    "item": {
        "name": "SCRIPT",
        "path": "/tmp/scripts"
    }
}
ok: [10.9.9.11] => (item={u'path': u'/tmp/MON', u'name': u'MON'}) => {
    "ansible_facts": {
        "allcmd": " ls -lrt /tmp/scripts | tail -57 && ls -lrt /tmp/MON | tail -57 &&"
    },
    "ansible_loop_var": "item",
    "changed": false,
    "item": {
        "name": "MON",
        "path": "/tmp/MON"
    }
}

After the loop completes I get the desired string except the fact that I'm left with the trailing && at the end i.e "allcmd": " ls -lrt /tmp/scripts | tail -57 && ls -lrt /tmp/MON | tail -57 &&".

I wish to remove the last 3 charecters i.e && from allcmd variable. Desired output:

"allcmd": " ls -lrt /tmp/scripts | tail -57 && ls -lrt /tmp/MON | tail -57"

Could not find any filters or fuction to remove last n charecters in ansible.

Can you please suggest ?

You can add the commands to a list (without `&&`) and `join(' && ')` the final list. — Zeitounator, Mar 02 '20 at 10:03
Very elegant solution @Zeitounator. Meanwhile I used `rstrip` filter to get the job done. — Ashar, Mar 02 '20 at 13:00

score 5 · Answer 1 · answered Oct 21 '21 at 20:51

5

there is a much easier way outlined in this link

http://www.freekb.net/Article?id=2884

  debug: 
    msg: "{{ 'Hello World'[:-3] }}"

answered Oct 21 '21 at 20:51

Jon Alexandar

131
1
10

1

For me, this is most elegant solution. – Peter Sivák May 10 '22 at 19:33
1

This specific kind of notation is called [Slicing](https://stackoverflow.com/a/509295/6771046). – U880D Jan 16 '23 at 10:46

score 1 · Accepted Answer · answered Mar 02 '20 at 23:13

- hosts: localhost
  vars:
    foo:
      - {"name": "SCRIPT", "path": "/tmp/scripts"}
      - {"name": "MON", "path": "/tmp/MON"}
  tasks:
    - debug:
        var: foo

    - set_fact:
        cmds: "{{ [ 'ls -lrt ' + item.path + ' | tail -57' ] + cmds | default([]) }}"
      loop: "{{ foo }}"

    - set_fact:
        allcmd: "{{ cmds | join(' && ')}}"

    - debug:
        var: allcmd

output:

ok: [localhost] => {
    "allcmd": "ls -lrt /tmp/MON | tail -57 && ls -lrt /tmp/scripts | tail -57"
}

Remove last n charecters from a string in Ansible

2 Answers2